INDIA  RUBBER, 

GUTTA-PERCHA,  AND  BALATA. 


•INDIA  RUBBER, 
GUTTA-PERCHA,  AND  BALATA-: 


Occurrence,  Geographical  Distribution,  and  Cultivation  of  Rubber  Plants; 

Manner  of  Obtaining  and  Preparing  the  Raw  Materials,  Modes  of 

Working  and  Utilizing  Them,  Including  Washing,  Loss  in 

Washing,  Maceration,  Mixing,  Vulcanizing,  Rubber  and 

Gutta-Percha  Compounds,  Utilization  of  Waste. 

Balata,  and  Statistics  of  Commerce. 


BY 


WILLIAM  T.  BRANNT, 

EDITOR  OF   "  THE  TECHNO-CHEMICAL  RECEIPT  BOOK.' 


ILLUSTRATED  BY  TWENTY-FOUR   ENGRAVINGS. 


PHILADELPHIA : 
HENRY  CAREY  BAIRD  &  CO, 

INDUSTRIAL  PUBLISHERS,  BOOKSELLERS  AND  IMPORTERS, 
810  WALNUT  STREET. 

LONDON : 
SAMPSON  LOW,  MARSTON  &  CO,  LIMITED, 

ST.  DUNSTAN'S  HOUSE,  FETTER  LANE,  FLEET  STREET. 
1900. 


COPYRIGHT  BY 
HENRY  CAREY  BAIRD  &  CO. 

1900. 


PRINTED  BY  THE 

WICKERSHAM  PRINTING  COMPANY 

53  and  55  North  Queen  Street, 

LANCASTER,  PA.,  U.  S.  A. 


PREFACE. 


IT  is  scarcely  necessary  to  enter  upon  the  import- 
ance of  the  rubber  industry,  or  of  the  great  trade  in 
rubber  which  has  now  developed  with  all  countries 
supplying  the  raw  material — a  trade  which  amounts 
to  fully  a  million  tons,  worth  more  than  $50,000,000 
a  year. 

Owing  to  the  peculiar  physical  and  chemical 
properties  of  rubber,  gutta  percha,  and  balata,  the 
industrial  applications  of  these  materials,  and  com- 
pounds of  them,  are  becoming  more  and  more  ex- 
tensive, and  for  some  branches  of  industry,  particu- 
larly electric  engineering,  they  are  indispensable. 

Although  rubber  and  gutta  percha  have  been 
worked  on  a  large  scale  for  scarcely  fifty  years,  the 
industry  has  developed  with  remarkable  rapidity, 
and  there  are  now  numerous  large  factories  exclu- 
sively engaged  in  working  these  useful  materials. 

The  aim  of  this  book  is  to  give  the  reader  a 
knowledge  of  the  raw  materials,  as  well  as  to  pre- 
sent the  industry  in  all  its  various  branches  as 
carried  on  by  the  most  progressive  manufacturers. 

(v) 

82897 


VI  PREFACE. 

With  this  object  in  view  all  the  available  informa- 
tion has  been  brought  together,  and  to  make  this 
information  as  complete  and  practical  as  possible 
the  researches  of  the  most  eminent  authorities  have 
been  consulted  and  drawn  upon. 

The  book  has  been  provided  with  a  copious  table 
of  contents  and  a  very  full  index,  which  will  render 
any  subject  in  it  easy  and  prompt  of  reference. 

\V.  T.  B. 

PHILADELPHIA,  March  1,  1900. 


CONTENTS, 


I.     INDIA  RUBBER. 
CHAPTER  I. 

RAW  MATERIAL. 

PAGE 

India  rubber  a  product  of  the  plant  organism  ;  Historical 
review ;  Shape  in  which  India  rubber  was  first  brought 
to  Europe;  La  Condamine's  discovery 1 

Description, by  Fresneau,  of  a  tree  yielding  India  rubber; 
Fuset-Aublet's  journey  to  Guiana  ;  Researches  of 
James  Howison  and  of  Roxburgh  ;  Description  of  a 
plant  yielding  milky  juice,  by  Coffigny;  Investigations 
of  Herissant  and  Macquer 2 

Priestley  on  the  application  of  rubber ;  Berniard's  ex- 
periments; Faujas  de  St.  Fond's  investigations  of 
mineral  caoutchouc ;  Foucroy,  Berthollet  and  Gio- 
bert's  studies  of  rubber;  Grossart's  invention;  Efforts 
of  Besson,  Johnson  and  others  to  prepare  water-proof 
garments  .  3 

^Commencement  of  the  actual  rubber  industry;  Nadier's 
invention;  Use  of  benzine  by  Charles  Mackintosh  for 
dissolving  lubber;  Thomas  Hancock's  investigations; 
Invention  which  established  the  permanency  of  the 
rubber  industry 4 

Luedersdorf's  observations;  Goodyear's  discovery  of  the 
process  of  vulcanizing  rubber 5 

First  introduction  of  vulcanized  rubber  shoes;  Hancock's 
process  of  vulcanization;  Parke's  process;  Augustin  G. 
Day's  improved  method;  Girard's  process;  Goodyear's 
invention  uf  hard  rubber:  Hancock's  invention  of  man- 
ufacturing rubber  articles  in  moulds 6 

(vii) 


Vlll  CONTENTS. 

PAGE 

Occurrence  of  India  rubber;  Rubber  contained  in  the 
milky  juice  of  milk-weed:  Habitat  of  the  actual  rub- 
ber-yielding plants;  Properties  of  the  milky  juice  or 
latex  of  rubber  plants  7 

Composition  of  the  best  quality  of  latex;  arrangement  of 
the  rubber  plants  in  four  families ;  EUPHORBIACE^K  : 
Hevea;  Micranda 8 

Manioc  or  manihot  (Plum  Adams);  Euphorbia;  ULMA- 
CE^;;  Castilloa;  Ficus 9 

Use  of  Ficus  elastica  as  an  ornamental  plant ;  Artocar- 
pus;  Cecropia;  APOCYNACE^E;  Vahea 10 

Landolphia;  Urceola;  Hancornia;  Cameraria  (Muller), 
Paramerio,  (Benth);  Leucomotis  (Jack)  . 11 

Ahtonia  (0.);  Chanemorphia  (G.);  ASCLEPIADE.*;;  Cy- 
nanchum  (L.);  Periploca  Graeca  (Z/.)l  Callatropis  pro- 
cera  (R.  Br.);   On  what  the  quality  and  quantity  of 
j    milky  juice  depend;  Age  at  which  trees  may  be  tapped    12 
•*  Arrangement  of  rubber  plants  into  geographical  groups  ; 
Soil  required  for  rubber  plants     , 13 

Cultivation  of  rubber  plants;  First  experiments  in  India 
with  the  native  Ficus  .  • .-  .  .  14 

Experiments  with  Urceola  elastica,  U.  esculcnta,  and  Cas- 
tilloa elastica ;  Robert  Cross'  journeys  to  Central  Amer- 
ica and  the  Amazon  River ;  Cultivation  of  rubber 
plants  in  the  Kew  Botanical  Garden 15 

Requirements  of  a  country  for  the  rational  cultivation 
of  rubber;  Unsuitability  of  the  territory  of  Assam;  Ac- 
climatizing experiments  with  Manihot  glaziovii.  .  .  16 

Mode  of  preparing  the  seed,  and  of  planting  ;  Formation 
of  plantation  by  cuttings 17 

Cultivation  of  Manihot  in  Ceylon;  Cultivation  of  the 
Para  rubber  tree  in  Ceylon 18 

Propagation  by  cuttings;  Mode  of  planting 19 

Age  at  which  the  trees  may  be  tapped ;  Cultivation  of 
rubber  trees  in  the  French  colonies ;  Experiments  at 
the  botanical  garden  at  Libreville 20 

Report  of  E.  Pierre;  Carelessness  of  the  natives  in  hand- 
ling young  plants 21 

Acclimatizing  experiments  in  Cochin-China;  Cultivation 


CONTENTS.  IX 

PAGE 

of  rubber  trees  in  Central  America;  Suitability  of  some 
portions  of  Mexico  for  that  purpose;  Castilloa  elastica 
and  its  occurrence  in  Mexico  • 22 

Gathering  and  preparing  the  seed;  Planting 24 

Forest  system  of  planting;  Starting  a  regular  plantation 
in  regular  orchard  form 25 

Setting  out  the  plants;  Protection  of  the  young  plants  .     26 

Xursery  for  young  plants ;  Transplanting  the  young 
plants  27 

Mode  of  setting  the  plants  in  Chiapas  and  Tabasco  ...     28 

Cost  of  establishing  a  rubber  plantation;  Manner  of  ob- 
taining crude  rubber ;  Methods  of  obtaining  milky 
juice;  Cutting  down  the  trees  for  this  purpose  ....  29 

When  cutting  down  the  trees  is  permissible;  Tapping  the 
trees  for  obtaining  the  milky  juice;  Method  employed 
on  the  lower  Amazon  river;  Tools  used  by  the  collector; 
Mode  of  making  the  incisions 30 

Manner  of  collecting  the  milky  juice ;  Average  yield ; 
Quantity  of  sap  obtained  from  each  tapping  of  150  trees  31 

Modes  of  tapping  on  the  Upper  Amazon,  Central  Amer- 
ica, Africa  and  Asia 32 

Methods  in  use  in  Australia;  Coagulation  of  the  latex  .     33 

Methods  by  \\hich  coagulation  is  effected;  By  artificial 
heat;  By  natural  heat;  By  skimming;  By  disintegra- 
tion    34 

By  natural  or  artificial  heat  in  combination  with  chemi- 
cal disintegration;  Description  of  the  various  processes 
of  coagulation :  Coagulation  by  artificial  dry  heat  or 
fumigation  ;  Preparation. of  Para  rubber 35 

Fumigation '.. 36 

Ellicacy  of  the  fumigating  process;  Composition  of  the 
milky  juice  of  Hecea  and  of  Micranda 37 

Fumigation  a  simple  means  of  rendering  substances  sub- 
ject to  putrefaction  or  fermentation  innocuous  ;  Grand- 
jean  and  AVasers  experiment  in  coagulation 38 

Preparation  of  some  kinds  of  Para  rubber  of  less  fine 
quality .  .  39 

Para  entrefina;  Sernamby  or  niggerhead;  Coagulation  of 
the  latex  by  means  of  riioist  artificial  heat  or  by  boil- 
ing; Method  in  use  by  the  Indians  of  Mexico 40 


X  CONTENTS. 

PA8B 

Defects  of  this  process;  Preparation  of  rubber  from  the 
latex  of  Castilloa  in  Mexico  ;  Coagulation  of  the  latex 
by  natural  heat — the  soil  as  a  means  of  separating 
water;  Use  of  this  method  in  Africa 41 

Method  employed  by  some  tribes  on  the  Congo  and  in 
Angola;  Coagulation  by  natural  heat,  evaporation  upon 
the  human  body 42 

Use  of  this  method  by  the  natives  of  East  Africa  and  by 
some  tribes  in  Angola;  Coagulation  by  natural  heat — 
evaporation  upon  other  even  surfaces  than  the  ground  43 

Mode  of  conducting  the  operation  in  Ceara;  Ceara  scraps    44 

Ceara  rubber  and  its  properties;  Improvement  in  the 
method  of  collecting  the  latex  of  Manihot 45 

Habitat  of  Manihot;  Coagulation  by  skimming  after  the 
addition  of  the  same  quantity  of  water,  and  a  shorter 
or  longer  rest;  Methods  employed  in  Bahia,  Nicaragua, 
Central  America  and  Assam 46 

Coagulation  by  rest  after  the  addition  of  four  to  five 
times  the  quantity  of  water;  R.  P.  Merlon's  descrip- 
tion of  the  method  employed  on  the  Congo  for  treat- 
ing the  latex  of  Landolphia 47 

Variety  of  rubber  known  as  "  thimbles ;"  Defects  in  the 
method  of  its  preparation;  Chemical  disintegration  by 
mineral  reagents 48 

Coagulation  by  alum;  Strauss'  process;  Objections  to 
this  process 49 

Coagulation  by  sulphuric  acid  and  sea  salt;  Coagulation 
by  soap  water .  50 

Description  of  this  process  by  E.  Bard;  Experiments  of 
Dr.  Morisse  in  treating  the  latex  of  Hevea 51 

Results  of  experiments  in  coagulation  with  various 
agents 52 

Most  effective  solutions 53 

Rousseau's  conclusions  regarding  the  various  methods 
of  coagulation  ....  54 

Chemical  disintegration  by  the  addition  of  vegetable 
agents;  Morellet's  conclusions  from  the  examination 
of  Madagascar  rubber;  Cousin's  experiments  ....  55 

Treatment  of  the  latex  of  Castilloa  in  Guatemala  and 


CONTENTS.  XI 

PAGE 

Nicaragua;  Coagulation  by  a  combination  of  natural 
or  artificial  heat  with  chemical  disintegration:  Method 
employed  with  Vahea  and  other  climbing  plants  ...  56 

Summary  of  the  results  of  experience  and  experiments 
in  coagulation 58 

Chemical  and  physical  properties  of  crude  rubber; 
Properties  of  the  fresh  latex  of  Hevea .  60 

Chemical  composition  of  the  latex  of  Hevea  brasiliensis; 
Variations  in  the  properties  of  crude  rubber;  Compo- 
sition of  crude  rubber 61 

Bodies  soluble  in  alcohol  contained  in  crude  rubber; 
Chemical  change  in  the  substance  of  rubber  produced 
by  light 62 

Effect  of  air  on  crude  rubber;  Gradual  oxidation  of  rub- 
ber; Content  of  water  in  good  rubber 63 

Decrease  of  content  of  carbon  in  rubber;  Effect  of 
water  on  rubber;  Behavior  of  rubber  towards  sulphur.  64 

Vulcanized  rubber;  Hard  rubber  or  ebonite;  Behavior 
of  rubber  towards  solvents  65 

Substances  capable  of  dissolving  rubber  in  the  actual 
sense  of  the  word ;  Results  of  experiments  as  to  the 
solubility  of  different  varieties  of  rubber 66 

Method  for  effecting  a  complete  solution  of  rubber     .   .     67 

Objection  to  the  use  of  carbon  disulphide  as  a  solvent; 
Mode  of  freeing  oil  of  turpentine  from  water  ....  68 

Solution  of  rubber  in  heated  linseed  oil;  Caoutchoucine 
or  oil  of  caoutchouc;  Most  suitable  solvents  for  prac- 
tical purposes;  Preparation  of  absolute  alcohol  ...  69 

Preparation  of  rubber  and  gutta-percha  solutions  accord- 
ing to  C.  Fry's  patented  method  .  . 70 

Behavior  of  rubber  in  heat;  Composition  of  crude  oil  of 
caoutchouc;  Composition  of  isoprene,  caoutchene,  and 
heveene  71 

Bodies  determined  as  being  present  in  oil  of  caoutchouc; 
Yield  of  isoprene,  caoutchene  and  heveene  from  11  Ibs. 
of  fresh  Para  rubber 72 

Most  effective  solvents  among  the  products  of  distilla- 
tion; Commercial  rubber;  Arrangement  of  the  vari- 
eties of  crude  rubber  in  three  principal  classes  ....  78 


Xll  CONTENTS. 

PAGE 

Summary  of  the  best  known  varieties,  including  their 
commercial  names,  place  of  origin,  form  in  which  they 
are  •  brought  into  commerce,  appearance,  properties, 
etc.;  AMERICAN  RUBBER:  South  America;  Fine  Para, 
Seringa  fina,  Borracha  or  Jebe;  Entrefine  Para,  i  fine 
Para,  Grossa 74 

Nigger  heads,  Para  Sernamby,  Sernamby  de  Borracha, 
Sernamby  de  Jebe,  Cabecja  de  negro;  Virgin  sheets  or 
Mattogrosso  Para  (Para  blanc);  Ceara  scraps  ....  75 

Pernambuco  (Mongabeira);  Maranham;  Bahia    .....      76 

Carthagena  (Esquebo);  Cuidad-Bolivar,  Columbia  Vir- 
gen;  Cayenne;  Peru  in  slabs  or  caucho 77 

Peruvian  balls,  Sernamby  de  Perou,  Seramby  de  Caucho; 
Guayaquil;  Central  America:  Colon  and  Panama; 
Mexican  and  other  Central  America  and  West  Indies 
sheets 78 

Guatemala;  Nicaragua. Mexico, Ecuador  and  West  Indian 
scraps;  AFRICAN  RUBBER;  Senegal  and  Bissao  balls.  79 

Gambia  balls;  Casamanza  (Boalam);  Casamanza  (Gam- 
bia)   80 

Sierra  Leone  Niggers;  Massai  Niggers;  Sierra  Leone 
twist;  Liberia;  Grand  Bassam;  Accrah 81 

Niger  Niggers;  Gaboon  Balls;  Gaboon  Tongues;  Kassai 
rouge;  Kassai  noir 82 

Kassai  noir  in  balls;  Kassai  strips;  Upper  Congo  (com- 
mon); Lrpper  Congo  (white);  Equator;  Lopari;  Busira; 
Aruwinri,  Mongala,  Buinba:  Uelle 83 

Lower  Congo  (thimbles);  Luvituku:  Loanda  thimbles; 
Loanda  Niggers 84 

Angola  Niggers  or  Nigger-heads;  Benguela  Niggers; 
Mozambique  Balls 85 

Mozambique  Spindles;  Madagascar,  black;  Madagascar, 
pinky;  Madagascar  Niggers:  ASIATIC  RUBBER;  Assam  86 

Rangoon;  Penang;  Ceylon;  Java  and  Padong 87 

Borneo;  Borneo  Djambes;  Borneo  (Ben  Koclen);  AUS- 
TRALIAN RUBBER;  New  Caledonia;  Statistics  ...  88 

Estimate  of  the  world's  production  and  consumption  of 
rubber;  Principal  market  for  crude  rubber  in  Europe; 
(Quantity  of  rubber  imported  by  Liverpool 89 


CONTENTS.  Xlll 

PAGE 

Importation  by  London  and   the   principal    European 

countries  together  with  the  United  States 90 

Prices  of  India  rubber 91 

CHAPTER  II. 

MECHANICAL  TREATMENT  OF  CRUDE  RUBBER. 

Removal  of  the  various  impurities  present  in  the  crude 

material;  Admixtures  found  in  crude  rubber     ....     92 
Manipulation  required  by  the  different  varieties  of  rub- 
ber; Softening  or  superficial  washing;  Cutting  up    .   .      98 

Cutting  machine,  illustrated  "and  described 94 

Rolling  or  washing;  Washing  machine,  illustrated  and 

described 95 

Use  of  hollow  rolls 97 

Drying 98 

Table  showing  loss  of  weight  by  washing  and  drying ; 

Further  working  of  the  washed  crude  rubber     ....      99 
Masticating  and  mixing  machine;   illustrated  and  de- 
scribed     100 

Variation  in  the  treatment  of  crude  rubber 101 

Fine-cut  sheets;  Methods  for  obtaining  blocks  of  rubber; 

Manner  of  cutting  up  the  blocks 102 

Scale  of  commercial  thickness  of  fine-cut  sheets;  Inven- 
tion of  the  manufacture  of  fine  cut  sheets  by  Charles 

Mackintosh 103 

Adulteration  of  fine-cut  sheet;  Cutting  square  threads 
from  pressed  blocks  ;  Preparation  of  mixed  mass  from 

washed  crude  rubber 104 

Nature  of  the  admixtures;  Manipulation  of  kneading  and 

mixing 105 

Mixing  machines 106 

Calender,  described  and  illustrated 107 

CHAPTER  III. 

VULCANIZ  ATION. 

Characteristic  peculiarities  of  crude  non-vulcanized  rub- 
ber; How  vulcanization  is  effected;  Experiments  of 
Anselme  Payen 109 


XIV  CONTENTS. 

PAGE 

Various  modes  of  vulcanization;  Cold  vulcanization,  in- 
vented by  Parkes 110 

Uses  to  which  cold  vulcanization  is  applied Ill 

Preparation  of  dichloride  of  sulphur 112 

Apparatus  for  the  preparation  of  dichloride  of  sulphur, 
described  and  illustrated ;  Properties  of  dichloride  of 

sulphur 113 

Preparation  of  anhydrous  petroleum;  Warm  vulcaniza- 
tion, invented  by  Hancock  114 

Girard's  process  of  vulcanization;  Preparation  of  penta- 

sulphide  of  potassium 115 

Advantage  of  Girard's  process lltt 

Another  process  of  vulcanization;  Mechanical  combina- 
tion of  rubber  with  sulphur;  Goodyear's  process  .  .  .  117 

Vulcanizing  operation 118 

Difference  of  opinion  as  to  the  degree  of  heat  required  for 
vulcanization;  Reasons  for  this  difference  in  opinion; 
Vulcanization  the  most  difficult  and  critical  operation 

in  the  manufacture  of  rubber  goods 119 

Limit  of  temperature  in  which  vulcanization  will  pro- 
gress in  a  correct  manner;  Conditions  on  which  the 

temperature  for  vulcanizing  depends        120 

Vulcanizing  apparatus ;  Brick  chambers  heated  by  hot 
air;  Vulcanizing  heaters  and  presses;  Ordinary  steam 

heater,  described  and  illustrated 121 

Vulcanizing  press,  described  and  illustrated 123 

Press  heated  by  petroleum,  described  and  illustrated  .   .    124 
Vulcanizing  operation ;    Mechanical  treatment  of  the 
articles;  Vulcanizing  articles  in  moulds;  Vulcanizing 

hose;  Metals  for  moulds 125 

Preventing  the  articles  from  sticking  to  the  moulds;  Pre- 
venting thick  sheets  from  warping;  Sorting  the  articles 
before  heating  ;  Vulcanizing  in  two  operations       .    .    12<> 
Modification  of  the  vulcanizing  process;  Process  for  arti- 
cles requiring  only  light  treatment;  Vulcanization  of 
articles  treated  with  saturated  solution  of  sulphur  in 
carbon  disulphide  ...  ....    127 

Vulcanization  with  an  addition  of  pentasulphide  of  anti 
mony;  Difference  in  the  action  of  commercial  penta 
sulphide  of  antimony;  Turner's  process 128 


CONTENTS.  XV 

CHAPTER  IV. 
RUBBER  COMPOUNDS. 

PAUE 

Substances  used  as  admixtures;  Coloring  matters    .   .   .    129 
Coloring  by  the  production  of  chemical  combinations  in 

the  mass;  Receipts  for  black,  green  and  violet  ....    130 
Admixtures  for  rubber  compounds  which  require  to  be 

rough;  Addition  of  black  pitch  for  cheap  products  .   .    131 
White  rubber  masses:  Cheap  rubber  masses,  with  an  ad- 
dition of  resin  132 

Metalized  rubber;  Preparation  of  vulcanized  rubber, 
which  does  not  swell  up  when  brought  in  contact  with 
fat;  To  make  rubber  pervious  to  perspiration;  Gerner's 
method  of  mixing  rubber  and  gutta  percha  with  cam- 
phor, cowrie  copal,  mustard  or  hemp  seed,  freed  from 

oil 133 

Kamptulicon  and  its  manufacture 134 

Uses  of  kamptulicon;  Coloring  of  kamptulicon 135 

Rubber  leather,  and  its  manufacture 136 

Balenite.  or  artificial  whalebone 137 

Plastite,  and  its  manufacture 138 

Formula  for  plastite  mass;  Grinding  and  polishing  com- 
positions; Substances  suitable  for  the  purpose   ....    139 
Formulas  for  sharpening  and  polishing  compositions  .   .    140 
Preparation  of  polishing  and  grinding  compositions.  .   .    141 

Rubber  enamel  and  its  preparation 142 

Preparation  of  colored  enamel 143 

Manner  of  applying  the  enamel;  Deodorizing  vulcanized 

rubber 144 

Various  processes  of  deodorizing  vulcanized  rubber  .   .   .    145 
Desulphurized  vulcanized  rubber;  Method  of  desulphur- 
izing    146 

Superiority  of  vulcanized  rubber  from  which  the  excess 
of  free  sulphur  has  been  removed. 147 

CHAPTER  V. 

HARD   RUBBER. 

Principles  upon  which  the  preparation  of  hard  rubber  is 

based;  Zinc  compound  recommended  by  Goodyear  .   .    148 
Substances  used  as  admixtures;  Uses  of  hard  rubber; 


XVI  CONTENTS. 

PAGE 

Marnier  of  combining  the  rubber,  sulphur  and  other 
ingredients 149 

Engel's  method  of  rilling  the  moulds;  Vulcanizing  hard 
rubber 150 

Coloring  hard  rubber;  Dusting  and  plating,  or  enamel- 
ing; Method  of  dusting 152 

Process  of  plating  or  enameling;  Admixture  of  indiffer- 
ent substances 153 

Coloring  substances; 'Utilization  of  waste 154 

Formulas  for  the  composition  of  hard  rubber;  Ebermay- 
er's  examination  of  hard  rubber  combs 155 

Formula  for  hard  rubber  possessing  great  hardness  and 
solidity,  with  but  little  elasticity;  Effect  of  an  admix- 
ture of  shellac  on  hard  rubber;  Formula  for  a  compo- 
sition with  shellac ...  156 

Newton's  mixture  for  buttons,  knife  handles,  etc.;  John- 
son's compound  for  brushes,  curry  combs,  etc.;  Use  of 
hard  rubber  in  the  manufacture  of  black  ornaments  .  157 

Physical  and  chemical  properties  of  hard  rubber.    .   .   .    158 

Preparation  of  artificial  ivory  159 

Decolorizing  and  bleaching  rubber 160 

Treatment  with  chlorine,  and  apparatus  used  for  this 
purpose,  described  and  illustrated 161 

American  process  of  bleaching  rubber;  Simplest  method 
of  bleaching  163 

Further  treatment  of  the  bleached  mass;  Incorporation 
of  different  substances  with  the  plastic  mass 164 

Different  ways  of  working  the  colored  masses;  American 
receipt  for  artificial  ivory 165 

CHAPTER  VI. 

MANUFACTURE  OF  ARTICLES  FROM  SOFT  RUBBER. 

Articles  made  from  fine  cut  sheets  and  their  manu- 
facture   " 167 

Rubber  toys 168 

Rubber  balls;  Hollow  articles 169 

Moulds  of  more  than  one  piece;  Acceleration  of  the 
evaporation  of  the  solvent;  Mixing  sulphur  with  the 
rubber  dough 170 


CONTENTS.  XV 11 

PAGE 

Preparation  of  small  solid  balls  of  vulcanized  rubber; 

Manufacture  of  small  toy  balloons 171 

Printing  rolls  for  use  in  dye  works;  Letellier  and  Ver- 
straat's  process  of  making  the  rubber  jacket  of  the 

pressure  rolls  of  cloth  printing  machines 172 

Preparation  of  rubber  threads;  Square  cords  from  crude 

rubber 173 

Machine  for  cutting  these  cords 174 

Simplest  manner  of  cutting  bands  into  threads;  Thread 

cutting  machine     175 

Cutting  square  cords  from  prepared  rubber 176 

Round  rubber  threads;  Aubert  and  Gerard's  process  .    .    177 
Diameter  of  threads  which  can  be  prepared  by  pressing; 

Preparation  of  thinner  threads;  Rubber  hose    ....    179 
Hose  or  tubing  for  chemists'  use;    Kinking  of  hose; 

Manufacture  of  ordinary  rubber  hose 180 

Cores  used;   Manufacture    of    short  tubing;    Hose   of 

greater  length  or  larger  diameter 181 

Rubber  hose  with  intermediate  layers  or  stiffeners;  Hose 

,  with  layers  of  wire;  Small  hose 182 

Tubing  machine  manufactured  by  John  Royle  and  Sons, 
of  Paterson,  N.  J.,  described  and  illustrated  ....  183 

"Rubber  sponge  or  moss  rubber 188 

Deodorizing  rubber  sponges;  Rubber  shoes 189 

Bicycle  tires;  Classes  of  pneumatic  tires 190 

Single  tube  tires;  Classes  of   compound  tires;  Dunlop 

tire 191 

Morgan  and  Wright  type  of  tire;  Manufacture  of  water- 
proof tissues;  First  use  of  rubber  for  this  purpose  by 
Chas.  Mackintosh  ;  Experiments  to  improve  Mackin- 
tosh's process 192 

Dumas'   suggestion  for    the    preparation  of  very  thin 

sheets;  First  improvement  in  Mackintosh's  process  .    .    193 
Character  of  the  tissues  to  be  waterproofed;  Preference 
for  closely  woven  fabrics;  Principal  requisite  of  ma- 
terials      194 

Preparation  of  fabrics  of  cloth  and  vulcanized  rubber    .    195 

Method  recommended  by  Johnson 196 

Difficulties  met  with  in  the  use  of  solutions;  Advan- 
tages of  using  rubber  compounds 197 


XV111  CONTENTS. 

PAGE 

Rubber  spreader,  described  and  illustrated 198 

Application  of  the  solution  by  means  of  ladles;  Protec- 
tion of  the  workmen  from  the  evil  effects  of  the  vapors.  200 
Apparatus  for  this  purpose,  described  and  illustrated  .   .    201 
Mode  of  operating  the  apparatus;  Best  plan  of  arranging 

the  work 2<)2 

Tissues  with  an  intermediate  layer  of  rubber;  Apparatus 

for  this  purpose,  described  and  illustrated 203 

Deodorizing  water-proof  fabrics 204 

Use  of  saturated  steam  for  this  purpose 205 

Manufacture  of  water-proof  fabrics  by  means  of  rubber 

compounds;  Preparation  of  compounds  with  linseed  oil.  206 
Properties  of  prepared  linseed  oil;  Dissolving  the  rubber; 
Application  of  the  solution;  Manufacture  of  rubber 
shoes  from  fabrics  water-proofed  by  means  of  rubber 

compounds 207 

Rubber  felt,  felt  paper,  or  Clark's  patent  felt 208 

Fabrication  of  elastic  webbings       209 

Mode  of  stretching  threads  to  be   used  for  webbing; 

Weaving  of  rubber  threads 210 

Another  method  of  preparing  elastic  webbings;  Use  of 

vulcanized  threads 211 

Recovery  of  solvents;  0.  A.  Burghardt's  condensing  ap- 
paratus, described  and  illustrated 212 

CHAPTER  VII. 

RUBBER   VARNISHES   AND   LACQUERS. 

Preparation  of  rubber  solutions 214 

Precautions  to  be  observed  in  the  use  of  carbon  disul- 
phide  and  of  benzene;  Increase  in  the  dissolving  power 

of  fluids  by  heat 215 

Apparatus  for  kneading  rubber  solutions,  described  and 

illustrated 216 

Receipts  for  rubber  varnishes;  Leather  lacquer    ....    218 
Varnish  for  gilders;  Varnish  for  glass;  Slow  drying  var- 
nish; Varnish  for  morocco 219 

Flexible  varnish;  Water-proof  coating  for  shoes  and 
boots;  Solution  for  repairing  rubber  shoes;  Marine 
glue 220 


CONTENTS.  XIX 

PAGE 

Marine  glue  for  damp  walls 221 

Jeffery's  marine  glue;    Transparent  cement  for  glass; 
Hard  rubber  lacquer 222 


II.  GUTTA  PERCHA. 
CHAPTER  VIII. 

RAW   MATERIAL. 

Historical  review  ;  Gutta-percha  first  brought  to  Europe 
by  John  Tradescant 224 

Observations  of  Dr.  Wm.  Montgomery  regarding  gutta- 
percha,  and  his  report  on  the  subject  to  the  Medical 
Board  at  Calcutta 225 

Experiments  by  English  manufacturers  with  gutta- 
percha;  First  patent  for  the  utilization  of  gutta-percha 
granted  to  Alexandre,  Cabriot  and  Duclos;  Attempts 
to  use  gutta-percha  for  articles  formerly  made  of 
rubber 226 

Use  of  gutta-percha  as  an  insulating  material;  First  tel- 
egraph lines  insulated  with  gutta-percha  constructed 
by  Werner  Siemens;  Wheatstone's  idea  of  connecting 
England  by  telegraph  with  the  Continent;  First  con- 
struction of  a  submarine  cable  by  Walter  Breit;  Occur- 
rence of  gutta-percha;  Plants  yielding  gutta-percha  227 

Dichopsis  gutta  or  Isonandra  gutta  or  Palagium  gutta; 
Dichopsis  oblong  if olium 228 

Dichopsis  calophylla  (Benth.  and  Hook.);  Dichopsis 
selendit;  Dichopsis  Krantziana;  Dichopsis  pustulatum; 
Payena  Lerii;  Bassia  Parkii;  Mimusops 229 

Geographical  distribution  of  trees  producing  gutta 
percha;  Manner  of  obtaining  crude  gutta  percha;  Time 
of  collection;  Tools  used  in  cutting  down  the  trees  .  .  280 

Various  ways  of  preparing  gutta  percha,  as  observed  by 
Leon  Brasse  and  Seligmann-Lui 231 

Scarcity  of  unmixed  gutta  percha   ...          232 

Variations  in  the  statements  regarding  the  yield  of  crude 
gutta  percha;  Danger  of  the  entire  exhaustion  of  the 
sources  .  .  .  233 


XX  CONTENTS. 


E.  Jungfleisch's  experiments  in  extracting  gutta  percha 

from  all  parts  of  the  tree;  Method  of  extraction  .  .  .  284 
Commercial  guttapercba;  Diversity  in  the  condition  of 
the  crude  product;  Mode  of  assorting  and  classifying 
gutta  percha  by  the  Chinese ;  Summary  of  the  best 
known  varieties  of  gutta  percha,  including  their  com- 
mercial names,  place  of  origin,  form  in  which  they  are 
brought  into  commerce,  appearance,  properties,  etc.; 

Pahang 2o(> 

Sandakan;  Maragula;  Bagan 2^7 

Banjer-massin;  Kotaringin;  Pekang:  Sarawak 238 

Pontianak;  Pedang;  Sarapong  or  Sauni 239 

Siak;  Bolungan  .   .       . 240 

Cote;  Cotonan;  Kelatan 241 

Pahang- white;  Assahan;  Tringanon 242 

Boula-Balam  ;  Statistics;  Quantity  of  gutta  percha 
brought  to  Singapore,  1885  to  1896,  calculated  by  Dr. 

E.  Obach 243 

Table  showing  the  quantities  imported  direct  from  Sing- 
apore into  the  various  countries ;  Table  showing  re- 
export from  England 244 

Table  showing  countries  which  received  the  re-export 
from  England 24-"> 

CHAPTER  IX. 

CHEMICAL  AND  PHYSICAL  PROPERTIES  OF  GUTTA-PERCHA. 

Properties  of  pure  gutta  percha 246 

Specific  gravity;  Pliability;  Behavior  in  the  cold  .    .    .   .    247 
Appearance  of  thin  sections  under  the  microscope;  Be- 
havior towards  solvents 248 

Chemical  composition  of  gutta  percha 249 

Payeifs  examination  of  gutta  percha;  Properties  of  pure 

gutta,  albane  and  fluavile 2>50 

Relation  between  gutta,  albane  and  iluavile;  Other  com- 
binations found  in  crude  gutta  percha;  Clark's  experi- 
ments upon  gutta  percha,  interpreted  by  W.  A.  Miller  2ol 
Examination  of  cables  which  had  been  submerged  for 
various  periods;  Chemical  indifference  of  gutta  percha: 
Behavior  towards'acids 2">,s 


CONTENTS.  XXI 

CHAPTER  X. 

TREATMENT  OF  CRUDE  C4UTTA  PERCHA. 

PAGE 

Examination  of  the  condition  of  the  crude  material;  Re- 

moval  of  stones  and  apparatus  for  this  purpose  ....  255 
Cutting  up  gutta  percha:  Drum  slicing  machine;  Wheel 

cutting  machine 256 

Separation  of  the  heavy  admixtures;  Washing  machine, 

described  and  illustrated  ....  257 

Kneading  machine;  described  and  illustrated 258 

Kneading  machines  with  horizontal  rolls,  described  and 

illustrated 259 

Manipulation  in  the  press  or  strainer;  Preparation  of  the 

cleansed  material  for  storage ...  260 

Rolling  the  gutta  percha  into  sheets,  and  machine  used 

for  this  purpose,  described  and  illustrated;  Mixture  of 

different  varieties  of  gutta  percha 261 

Loss  in  washing  and  kneading  262 

CHAPTER  XI. 

INDUSTRIAL  APPLICATION  OF  GUTTA  PERCHA. 

Principal  uses  of  gutta  percha 263 

Moulding  articles  from  gutta  percha;  Gutta  percha  hose; 

Machine  used  for  this  purpose 264 

Mode  of  operation      265 

Machines  for  the  manufacture  of  hose  of  any  desired 

length 26H 

Modification  of  the  press  used  for  the  manufacture  of 
hose  for  preparing  solid  articles ;  Gutta-percha  threads  267 

Apparatus  for  preparing  threads  .   . 268 

Manufacture  of  threads  by  rolling;  Coating  wires  with 

gutta  percha. 269 

Insulation  of  telegraph  wires;  Manufacture  of  telegraph 
cables;  Apparatus  for  coating  wire  with  gutta  percha, 

described  and  illustrated 270 

Further  protection  of  the  cable 272 

Machine  for  insulating  electric  wire  and  cables,  manu- 
factured by  John  Royle  &  Sons.  Patterson,  N.  J.,  de- 
scribed and  illustrated  .  273 


XX11  CONTENTS. 

I'Aiil-: 

Vulcanization  of  gutta  percha;  Mixture  recommended 
for  the  purpose 27i> 

Process  of  vulcanizing  gutta  percha  with  chloride  of  sul- 
phur  277 

CHAPTER  XII. 

BLEACHING  OF  GUTTA  PERCHA— GUTTA  PERCHA 
COMPOUNDS. 

Bleaching  agents  used;  Bleaching  with  chloroform.   .    .    278 

Process  for  obtaining  an  entirely  decolorized,  pure  white 
product;  Apparatus  for  this  purpose,  described  and 
illustrated 27',» 

Cattell's  bleached  gutta  percha 281 

Gutta  percha  compounds;  Use  of  compounds  of  rubber 
and  gutta  percha  in  galvanoplasty;  Gutta  purcha  sheets 
for  taking  impressions  of  coins,  medals,  etc.  .  .  282 

Mixture  of  rubber  and  gutta  percha  for  overlapping  ma- 
trices or  moulds;  Gutta  percha  and  rubber  compounds 
for  machine  belts;  Formula  of  a  compound  for  this 
purpose ....  283 

Manufacture  of  belts 2S4 

Hard  gutta  percha  compounds;  Materials  used  for  white 
and  colored  articles;  Total  weight  of  the  materials 
added 2.sf> 

Methods  of  disguising  the  odor  of  gutta  percha;  Corn- 
pound  of  gutta  purcha  and  wood .  286 

Sorel's  gutta  percha  compounds;  Formula  for  the  best  of 
Sorel's  compounds ;  Manner  of  preparing  the  com- 
position   2<s(s 

Various  receipts  for  manufacturing  Sorel's  gutta  percha 
compounds;  Rousseau's  solutions  of  gutta  percha  and 
their  use 2<s<) 

Chatterton's  gutta  percha  compound 2JK) 

CHAPTER  XIII. 

RUBPER  AND  GUTTA-PERCHA  WASTE  AND  ITS  UTILI/ATION. 

Distinction  between  waste  from  pure  and  from  vulcan- 
ized rubber:  Utilization  of  pure  crude  rubber  waste: 
Manipulation  of  wafcte  of  vulcanized  rabber 2J»i 


CONTENTS.  XX111 


Aco's  process  of  utilizing  waste 292 

Another  method  of  utilizing  vulcanized  rubber  waste; 

Newton's  method 293 

Utilization  of  waste  of  gutta-percha 294 

CHAPTER  XIV. 

EXAMINATION  OF  RUBBER   ARTICLES. 

Difficulty  in  deciding  how  far  admixtures  are  to  be  con- 
sidered serviceable  or  as  adulterations;  A  clue  to  the 
extent  of  admixtures  afforded  by  the  determination  of 
the  specific  gravity .  .  205 

Slight  increase  in  the  specific  gravity  by  the  addition  of 
sulphur;  Table  of  determinations  showing  the  increase 
in  the  specific  gravity  by  the  addition  of  mineral  sub- 
stances   29K 

Determination  of  the  specific  gravity;  Difficulties  met 
with  in  an  accurate  examination  of  rubber  articles; 
Determination  of  the  total  quality  of  filling  substances  2i>7 

Unger's  directions  for  examining  articles  vulcanized 
with  pentasulphide  of  antimony;  Determination  of 
sulphur 298 

Henriques'  method 299 

Determination  of  antimony;  Determination  of  calcium  .  300 

Results  obtained  by  Unger  in  examining  a  sample  of 
rubber 301 

Determination  of  other  mineral  filling  substances;  De- 
tection of  admixtures  of  organic  substances;  Henriques' 
method  of  detecting  a  content  of  oily  substitutes  .  .  302 


III.  BALATA. 
CHAPTER  XV. 

HISTORY,  OCCURRENCE  AND  USES  OF  BALATA. 

Balata  made  known,  in  1857,  by  Prof.  Bleekrode;  Speci- 
mens forwarded  to  the  Kew  Museum  ........  303 

Distribution  of  the  genus  Mimusops;  Habitat  of  trees 
yielding  balata;  Mimusops  Balata 304 


XXIV  CONTENTS. 

PAGE 

Varieties  of  Mimusops  which  yield  balata;  Mode  of  col- 
lecting balata  in  Venezuela 305 

Methods  of  collecting  balata  in  Dutch  Guiana  and  in 
British  Guiana 30(i 

Properties  of  crude  balata;  Impurities  in  the  com- 
mercial article;  Great  value  of  balata  from  Mimusojix 
JJalata  and  M.  globosa 307 

Table  showing  price  and  export  of  balata  from  British 
and  Dutch  Guiana 308 

Principle  difference  between  gutta-percha  and  balata    .    309 

Manner  of  working  crude  balata 310 

Uses  of  unmixed  balata;  Manufacture  of  balata  machine 
belts;  Joining  the  ends  of  belts,  described  and  illus- 
trated   311 

Index  .  .    314 


UlN  ^TY 


INDIA  RUBBER, -GOTTA  PIRCHA,  BALATA. 


I.  INDIA  RUBBER. 
CHAPTER  I. 

RAW    MATERIAL. 

INDIA  RUBBER,  or  caoutchouc,*  is  a  product  of 
the  plant  organism.  Together  with  other  solid  and 
liquid  bodies,  it  is  very  likely  formed  as  a  milky 
fluid  in  separate  vessels  by  the  conversion  of  tissue- 
mass,  and,  on  the  juice  drying  up,  remains  behind 
with  other  solid  substances  present.  According  to 
some  botanists,  it  is  a  never-wanting  constituent  of 
every  vegetable  milky  juice,  occurring  also  in 
opium.  The  commercial  article,  however,  is  ob- 
tained from  various  trees  of  the  tropical  and  semi- 
tropical  regions. 

Historical  Review. 

India  rubber  in  the  shape  of  bags  and  bottles  was 
first  brought  to  Europe  in  the  commencement  of 
the  eighteenth  century,  but  neither  its  nature  nor 
origin  was  known.  In  1735,  La  Condamine  first 


Latin,  gummi  elasticum ;    German,   gum/mi;    French, 
;  Spanish,  seringa;  Portuguese,  xirringa. 

(i) 


2      INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

discovered  that  the  substance  was  the  dried  milky 
juice  of  a  tree,  which  the  Indians  on  the  coast  of  the 
Amazon  River  called  Caout-Chou,  and  from  which, 
from  time  immemorial,  they  had  been  making 
water-proof  fabrics,  shoes,  vessels,  etc.  Fresneau,  who 
had  settled  in  Cayenne,  described,  in  1751,  a  tree 
yielding  India  rubber,  and  to  thia  indefatigable  ex- 
plorer we  are  indebted  for  the  first  exact  description 
of  the  method  employed  by  the  natives  for  obtain- 
ing it.  The  researches  of  La  Condamine  and  Fres- 
neau caused  the  French  botanist  Fuset-Aublet  to 
make,  in  1756,  a  journey  to  Guiana.  Two  years 
later  he  published  his  work  on  the  Flora  of  Guiana, 
in  which  he  described  the  rubber  tree,  and  applied 
to  it  the  name  Hevea  guyanensis.  James  Ilowison, 
a  physician  residing  in  Prince  of  Wales  Island,  an 
island  of  the  Malay  Archipelago,  first  determined 
the  species  yielding  an  "  elastic  gum  wine,"  and 
Roxburgh  later  on  applied  the  name  Urceola  elastica 
to  this  species.  The  latter  also  discovered  in  Assam, 
in  the  forest  on  the  shores  of  the  Brahmapootra,  the 
Ficus  elastica.  Finally  Coffigny  described  a  vine- 
like  plant  of  Madagascar  belonging  to  the  jasmine 
family,  which  also  yields  a  milky  juice.  When 
dried  this  juice  forms  an  elastic  resin  resembling 
rubber. 

While  the  botanists  studied  the  rubber-yielding 
plants,  the  chemists  investigated  the  new  resin,  and 
succeeded  in  dissolving  it.  In  1768,  Herissant 
and  Macquer  communicated  simultaneously  to  the 
Paris  Academy  the  results  of  their  investigations, 


RAW    MATERIAL.  o 

and  called  attention  to  the  fact  that  india  rubber, 
which  is  insoluble  in  water  and  alcohol,  may  be 
softened  and  even  dissolved  in  oil  of  turpentine  and 
pure  ether.  At  the  same  time  they  proposed  the 
employment  of  the  softened  resin  for  the  manu- 
facture of  surgeons'  probes  and  small  tubes  for  use 
in  the  laboratory.  The  celebrated  English  chemist 
Priestley,  in  1770,  called  the  attention  of  scientists  to 
the  useful  application  of  india  rubber  by  recom- 
mending it  for  effacing  lead-pencil  marks.  The 
experiments  of  the  French  chemist  Berniard  (1780) 
completed  the  labors  of  Herissant  and  Macquer,  and 
foreshadowed  the  many  uses  to  which  india  rubber 
might  be  applied  in  the  future.  Faujas  de  St. 
Fond  occupied  himself  in  the  investigation  of  a  kind 
of  resin  found  in  the  mines  at  Castelton,  and  called 
it  mineral  caoutchouc.  Foucroy,  Berthollet  and 
Giobert  also  wrere  interested  in  the  study  of  india 
rubber.  Grossart  invented  the  most  simple  process 
of  making  from  bottles  of  Brazilian  rubber,  tubes  and 
other  articles  for  physical  and  surgical  purposes,  as 
well  as  for  household  use.  For  the  preparation  of 
small  tubes,  he  cut  the  bottles  into  strips  of  suitable 
size,  softened  them  by  placing  them  for  half  an 
hour  in  ether,  or  somewhat  longer  in  volatile  oil, 
rolled  the  strips  upon  a  mandrel,  and  pressed  them 
strongly  by  means  of  a  rope  wound  spirally  around 
them.  On  drying,  the  surfaces  adhered  together, 
and  the  pieces  retained  tho  shape  given  to  them. 

There   may  be  mentioned  here  the  more  or  less 
successful  efforts  of  Bessoii  (1791),  Johnson  (1797), 


INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

Champion  (1811),  and  Clark  (1815),  to  prepare 
water-proof  garments  by  means  of  rubber  solutions. 
Hut  the  actual  rubber  industry  dates"  only  from 
1820.  About  this  time  Nadier  invented  a  process 
of  cutting  rubber  into  threads,  and  of  manufactur- 
ing tissues  from  the  latter.  Charles  M  akin  tosh,  in 
1823,  used  benzine  for  dissolving  rubber,  and 
created  thereby  the  industry  of  the  water-proof  gar- 
ments which  are  named  after  him. 

But,  nevertheless,  the  useful  application  of  india 
rubber  still  presented  many  difficulties.  The  ma- 
terial was  not  easy  to  work,  required  special  con- 
trivances, and  the  still  incomplete  methods  of  dis- 
solving it  rendered  it  difficult  to  give  definite  shape 
to  the  articles. 

These  difficulties  were  overcome  in  1836,  when  it 
was  found,  as  the  result  of  investigations  by  Thomas 
Hancock,  that  india  rubber  cut  into  strips,  or 
passed  between  rolls  and  subjected  to  energetic 
kneading,  can,  under  the  influence  of  moderate 
heat,  be  converted  into  a  tough  mass:  furthermore, 
that  its  elasticity  is  temporarily  suspended,  and  that 
in  this  state  it  can  be  given  any  desired  shape.  By 
reason  of  these  observations  and  discoveries,  the 
industry  made  rapid  progress. 

However,  the  permanency  of  the  industry  would 

L  •/        «  i 

have  been  doubtful  if  it  had  not  been  for  another 
invention  of  still  greater  importance  than  the  pre- 
ceding. Besides  its  impermeability  and  great  elas- 
ticity, natural  rubber  possesses  the  property  of  being 
extraordinarily  adhesive  at  an  ordinary  tempera- 


RAW    MATERIAL.  O 

tore,  especially  so  when  two  pieces  of  it  come  in 
contact  with  each  other.  It  shows  this  peculiarity 
to  a  still  greater  extent  at  a,  higher  temperature,  so 
that  it  becomes  sticky  and  pitch-like,  and  diffuses  a 
very  disagreeable  odor,  but  loses  it  entirely  in  the 
cold,  it  becoming  brittle,  and  breaking  when  ex- 
tended. 

The  German  chemist  Luedersdorf  first  noticed,  in 
1832,  that  sulphur  deprives  rubber  dissolved  in  oil 
of  turpentine  of  its  stickiness.  Hay  ward  at  the 
same  time  used  flowers  of  sulphur  for  scattering 
upon  rubber  leaves,  weakening  thereby  the  adhesive 
power.  Neither  one  of  them,  however,  investigated 
the  subject  any  further,  and  it  remained  for  Charles 
Goodyear,  in  1839,  finally  to  settle  the  question  of 
an  india  rubber  useful  in  every  respect,  and  to 
prepare  a  material  which  would  not  break  at  .a 
lower  temperature  nor  stick  together  at  a  higher. 

The  discovery  of  Goodyear  consisted  in  that  he 
first  subjected  the  rubber  to  the  action  of  sulphur, 
and  then  exposed  it  to  quite  a  high  temperature. 
This  process  is  called  vulcanization,  and.  rubber  thus 
treated,  vulcanized  rubber.  Vulcanized  rubber  ( re- 
tains its  elasticity  at  a  high  temperature  (up  to, 
248°  F.)  as  well  as  at  a  low  one  (to  —22°  F.),  and 
besides  offers  greater  resistance  to  chemical  in- 
fluences. 

The  discovery  of  vulcanization  gave  great  impetus 
to  the  rubber  industry,  and  rendered  possible  its 
almost  unlimited  development,  and  in  the  succeed- 
ing twenty  years  .nearly  every  day  brought  new 


O      INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

discoveries  and  improvements.  Goodyear  patented 
his  process  of  vulcanizing  by  mechanical  means, 
and,  as  early  as  1842,  brought  rubber  shoes  into 
market  which  retained  their  elasticity  in  the  cold, 
and  hence  were  vulcanized.  Shortly  after  Good- 
year's  discovery,  Hancock  succeeded  after  many 
experiments  in  preparing  a  product  similar  in  all 
respects  to  Goody  ear's.  He  immersed  the  rubber 
in  melted  sulphur,  allowing  it  to  remain  until 
entirely  permeated,  and  then  exposed  it  to  a  tem- 
perature of  302°  F.  He  patented  this  process  in 
England  in  1843.  Parkes,  in  1843,  first  employed 
carbon  disulphide  for  dissolving  rubber,  and  later 
on  patented  the  method  of  "  cold  vulcanization,"  or 
vulcanizing  by  means  of  chloride  of  sulphur.  lie 
also  invented  the  method  of  desulphurizing  vulcan- 
ized rubber  waste.  In  1858,  Augustin  G.  Day 
took  out  a  patent  for  an  improved  method  of  vul- 
canizing, and  Girard  proposed  alkaline  sulphur  for 
vulcanizing  thin  articles.  The  last  great  invention 
was  that  of  hard  rubber  by  Goodyear,  who  succeeded 
in  obtaining  a  horn-like  mass  resembling  whale- 
bone or  ivory. 

Finally  a  patent  may  be  mentioned  which  was 
granted  to  Hancock,  in  1846,  for  the  manufacture 
of  rubber  articles  in  moulds,  an  invention  which, 
next  to  that  of  vulcanizing,  has  become  the  initia- 
tory step  towards  the  entire  present  manufacture  of 
rubber  articles,  and  has  created  an  immense  in- 
dustry. 


RAW    MATERIAL.  t 

Occurrence  of  India  Rubber. 

As  previously  mentioned,  some  botanists  claim 
that  rubber  is  a  constituent  part  of  every  vegetable 
milky  juice.  Many  plants  carrying  milky  juice  are 
indigenous  to  temperate  climates,  but  they  contain 
either  no  rubber  at  all,  or  the  quantity  is  so  small 
that  it  would  not  be  worth  while  to  make  an  at- 
tempt to  gain  it  on  a  large  scale.  It  is  claimed 
that  the  milky  juice  of  milkweed  (Asclepias)  con- 
tains four  per  cent,  of  rubber,  and  some  years  ago  a 
company  was  formed  in  Canada  for  the  purpose  of 
obtaining  rubber  from  this  source,  but  we  have 
been  unable  to  learn  anything  further  in  regard  to 
this  enterprise,  and  believe  that  the  scheme  has 
collapsed. 

The  habitat  of  the  actual  rubber-yielding  plants 
is  limited  to  tropical  and  semi-tropical  regions  be- 
tween about  the  30th  degree  of  northern  and  the 
30th  degree  of  southern  latitude.  In  these  regions 
there  extends  around  the  globe,  parallel  with  the 
equator,  a  belt  nearly  500  miles  in  width,  which 
possesses  all  the  requisites  for  the  propagation  of 
rubber  plants.  The  climate  is  warm  and  moist, 
the  temperature  varying  between  79°  and  107°  F., 
and  the  average  annual  rain-fall  being  about  7  feet. 
The  milky  juice,  or  latex  of  the  rubber  plants  of 
these  regions  is  of  about  the  density  of  cream,  pos- 
sesses a  slight  odor  of  amber,  is  miscible  with  wrater, 
but  not  with  naphtha,  nor  with  any  other  substance 
which  dissolves  rubber.  Its  specific  gravity  is  from 
1.02  to  1.11,  while  that  of  rubber  is  0.930.  There 


8      INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

is  considerable  variation  in  its  content  of  pure  rub- 
ber, the  best  quality  of  latex,  that  of  Para,  Brazil, 
having  the  following  composition  : 

Pure  rubber         .         .         .32  per  cent. 
Albumen  and  mineral  con- 
stituents .         .  12       " 
Water          .         .         .         .     50 
The  rubber  plants  may  be  arranged  in  four  fam- 
ilies as  follows : 

1.  EUPHORBIACE^E  :  Hevea,  Micranda,  Manioc  or 
Manihot,  Euphorbia. 

a.  Hevea  is  a  variety  of  Euphorbiacese  and  belongs 
to  the  Jatrophess:     The  tree  is  very  large  and  con- 
tains much  milky  juice.     It  is  readily  propagated, 
the  capsules  containing  the  seeds  bursting  with  a 
report  like  that  of  a  rocket,  and  the  seeds  are  scat- 
tered a  distance  of  50  to  60  feet. 

Up  to  very  recent  times  Hevea  Giiyanensis  (called 
by  Linne  Jatropa  elastica,  and  by  Schreber,  Siphonia 
elastica)  has  been  incorrectly  designated  as  the 
actual  rubber  tree  called  by  the  Indians  of  Brazil 
Seringa  or  Cahuchu.  '  To  be  sure  Hevea  Guyanensis 
is  the  tree  described  by  La  Condamine  and  Fros- 
neau,  but  it  yields  veiy  little  latex,  which  besides 
contains  not  much,  and  even  not  very  good,  rubber. 
The  species  of  Hevea  which  yields  the  largest  quan- 
tity and  the  best  quality  of  rubber  is  Hevea  Brasil- 
iensis  or  Siphonia  Brasilicnsis. 

b.  Micranda  (Benth.)   is  a  tree-like  cujtliorbiacea 
belonging  to  the   Jatrophese.     It  is  indigenous  to 
Brazil  where  three  or  four  varieties  are  known  to 
occur. 


RAW    MATERIAL.  9 

c.  Manioc  or  maniliot  (Plum-Adams),  a  variety  of 
Jatrophese.     Seventy-five  species  (herbs  and  shrubs) 
of  it  are  indigenous  to  South  America.     The  root  is 
very  rich  in  starch,  and  is  an  important  article  of 
food  in  the  tropics.     From  Manihot  utilissima  and 
J/.  Hipii  cassava  and  tapioca  are  prepared. 

Manihot  Glazoivii  or  leitera  yields  the  rubber 
known  in  commerce  as  Ceara  scraps y  called  by  the 
natives  manisoba.  It  grows  in  dry,  rocky  soil  on 
mountains,  while  Hevea  flourishes  in  moist  low 
lands  and  requires  a  clayey  soil. 

d.  Euphorbia.     This  is  a  genus  of  many  species, 
mostly    shrubby,   herbaceous   succulents,  affording 
an  acrid  milky  juice  which  draws  blisters.     Thus 
far  they  have  been  but  little  utilized,  but  it  may  be 
supposed  that  in  the  future,  more  energetic  attempts 
will  be  made  to  obtain  rubber  from  them. 

2.  ULMACE.E,  a  genus  of  Artocarpefe :  Different 
varieties  of  Castilloa,  Ficus,  Artocarpus  and  Cecropia. 

a.  Castilloa,  a  variety  of    Ulmacese  of  the  family 
ArtocdTpese,  is   indigenous  to  Mexico,  U.  S.  of  Co 
lumbia,  entire  Central  America,  the  Antilles  and 
Martinique. 

b.  Ficus  belongs  to  the  family  of  Ulmacese,  divi- 
sion Artocarpess.     The  genus  Ficus  is  very  numer- 
ous, there  being   known   more   than   600   varieties 
which    are   indigenous    to  the   tropical   and   warm 
moderate  zones.     Its  widest  distribution  is  in   the 
Indian  Archipelago  and  the  islands  of  the  Pacific 
Ocean.       While    Castilloa    is    the  "rubber    tree    of 
Mexico  and  Central  America,  the  Ficus  is  the  rub- 


10     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

her  tree  of  East  Asia  and  Australia.     In  Africa  and 
America  it  is  but  seldom  found. 

Of  the  Ficus  varieties,  Ficus  elasti&t  is  frequently 
seen  here  in  hot  houses,  and  is  employed  as  an 
ornamental  house-plant.  It  has  large,  leathery, 
oval  and  entire  leaves,  which  are  dark  green  and 
glossy  above.  It  is  readily  propagated.  A  few 
shoots  are  allowed  to  grow  until  they  have  four  or 
five  leaves,  and  are  then  used  in  spring  as  cuttings. 
They  are  placed  in  a  bottle  full  of  water,  and  small 
white  roots  soon  develop  from  the  cut  surfaces. 
The  best  soil  for  Ficus  elastica  is  a  mixture  of  leaf 
and  wood  mould. 

c.  Artocarpus  is  a  tree   belonging  to  the   family 
Ulmacete.     About  twenty  varieties  of  it  are  known 
to  occur  in  Asia  and   Australia.     The  nearly  ripe 
pistillate  inflorescence,  known  as  breadfruit,  forms  a 
globular  sorosis  about   0   inches  in   diameter,  and 
consists  of  a  mealy  and  spongy  receptacle  in  which 
the   oblong    angular  akenes    are    imbedded.      The 
latex  of  Artocarpus  is  viscous,  and  is  used  by  the 
natives  in  the  preparation  of  bird-lime.     The  fruit 
forms  an  important  article  of  food. 

d.  Cecropia  (Locfl.)  a  variety  of  Ulnmcai   belong- 
ing to  the    CkmoGephalese.      Indigenous  to  Central 
and  South  America, 

3.  APOCYXACE.K  :  V&rietieaofLandolpkia,  lTireola, 
Dijera,  Hancortiia,  Camemria,  Paramrrni,  l,<'ncnnntis, 
Artodendron,  Alstonia  and  Ghonemorphia. 

a.  Vahea  a  genus  of  AjtocymH-ni ,  which  embraces 
about  twenty  species  of  lianas  (climbing  shrubs) 


RAW    MATERIAL.  11 

indigenous  to  Central  Africa  and  Madagascar.  The 
fruit  is  a  large  berry  with  eight-cornered  seeds  with 
hard  perisperm. 

b.  Landolpliia     (Pal.     Beauc.}.       This     climbing- 
shrub   is  generally  considered  a  species  of  Valiea, 
but  according  to  M.  Radelkoffer,  it  is  a  separate 
species. 

c.  Urceola.       This    family    comprises    about    six 
species  of  climbing  shrubs  indigenous  to  the  Ma- 
layan Archipelago. 

d.  Hancornia.     The  various  species  of  Hancornia 
are  small   trees  containing  milky  juice.     They  are 
indigenous  to  South    America,  and  yield   a  good 
quality  of  rubber.     The  fruits  of  Hancornia  speciosa 
(Gom.)  and  of  H.  Pubescens  (Nees.  and  Mart.)  are 
known  as  mangaba,  and  are  highly  esteemed  by  the 
natives. 

e.  CanK.raria  (Mailer)   a   variety   of  Apocynacese, 
order  Plumericese,  indigenous  to  the  Antilles,   are 
shrubs  of   which    C.  lucida  and    C.   latifolia  (Jack) 
yield  rubber. 

/.  Paraineria  (Benth.),  a  variety  of  Apocynacese- 
Nericese  and  allied  to  the  Eidysantlierex.  To  this 
genus  belong  two  or  three  climbing  shrubs  indig- 
enous to  Asia  and  tropical  Oceanica,  Paraineria 
Pierrei,  indigenous  to  Cambodia,  yields  excellent 
rubber. 

g.  Leuconotis  (Jack)  a  variety  of  Apocynaceae- 
Carisseae.  To  this  genus  belong  two  shrubs  con- 
taining milky  juice,  which  are  indigenous  to  the 
Malayan  Archipelago. 


12     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

li.  Alstonia  (('.),  a  beautiful  tree  indigenous  to 
tropical  Asia  and  Australia.  The  latex  is  very 
bitter. 

i.  Chonemorphia  (G.),  a  plant  of  the  variety  Apo- 
cynacese,  sub-division  Euechitidesc.  It  is  a  vine-like 
climbing  plant,  three  or  four  species  of  which  are 
known  to  occur  in  the  East  Indies  and  in  the 
Malayan  Archipelago. 

4.  AscLEPiADEyK  :  Callotropis,  ('i/mniclniin,  and 
Periploca. 

a.  .Cy,ianchuin  (Z/.),  a  climbing  plant  of  the  family 
Asdepiadese,  genus  Oynanchese,  indigenous  to  Africa. 

6.  Periploca  Grwca  (L.\  a  slender  climbing  shrub 
which  contains  milky  juice,  is  indigenous  to  Africa. 

c.  Callotropis  procera  (P.  Br.),  a  shrub  6  to  10  feet 
high,  indigenous  to  Northern  India  and  westward 
through  Asia  and  tropical  Africa.  It  carries  beau- 
tiful large  flowers  of  a  rose  and  purple-red  color. 

It  will  be  readily  understood  that  the  quantity  of 
milky  juice  in  the  varieties  of  plants  above  enu- 
merated not  only  varies,  but  is  also  dependent  on  the 
age  of  the  plant,  the  nature  of  the  soil,  the  season 
of  the  year,  and  even  on  the  time  of  the  year  when 
it  is  obtained.  It  is  also  evident  that  the  quality 
of  the  milky  juice,  and  consequently  of  the  rubber, 
depends  on  the  manner  in  which  the  latex  is  ob- 
tained and  the  globules  of  rubber  are  separated. 

While  Hevea  brasliensis  must  attain- an  age  of  at 
least  15  to  20  years  before  it  can  be  tapped  for 
milky  juice,  and  reaches  the  height  of  productive- 
ness when  25  years  old,  which  to  be  sure  it  retains 


HAW    MATERIAL.  13 

to  an  age  of  100  years,  Manioc  yields  milky  juice  in 
10  years,  and  Urceola  even  in  5  years.  Climate 
exerts  an  important  influence  upon  the  quality  as 
well  as  upon  the  quantity  of  the  milky  juice.  Gen- 
erally speaking,  it  may  be  said  that  the  yield  is 
remunerative  only  in  the  tropical  zone,  that  is  where 
the  temperature  varies  between  68°  and  104°  F.  In 
the  temperate  zone,  between  the  30°  northern  and 
30°  southern  latitude,  great  variations  occur,  so 
that,  for  instance,  a  plant  which  flourishes  exuber- 
antly in  Brazil,  cannot  be  acclimatized  in  India. 
According  to  climatic  conditions,  the  principal 
rubber  plants  may  be  arranged  in  the  following 
geographical  groups  : 

South  America  (plains)  :  Hevea,  MicrcnuJa. 

South  America  (mountains)  :  Manioc,  Hancornia. 

Central  America  :   Cast-Ulna. 

West  Africa  :  Landolphia,  Vahea,  Callotropis. 

East  and  Central  Africa  :    Vahea,  Landolphia. 

India  :   Fini*.  WUlughbeia,  Cynanchum,  Cameraria, 


Australia  :  Ficus,  Urceola. 

It  has  been  generally  supposed  that  all  rubber 
plants  require  a  moist  soil  exposed  to  the  tropical 
sun.  Such,  however,  is  only  the  case  with  Hevea 
braxiliejtsis.  Hancornia  flourishes  in  the  sandy  tracts 
of  Pernambuco,  Maranham  and  Bahia,  and  Manioc 
upon  the  steep  granite  rock  of  Ceara  or  Clara.  The 
last-named  plants  withstand  even  extraordinary 
drought.  While  everything  else  is  destroyed  by  the 
hot  wind,  these  plants  flourish  and  yield  an  abund- 
ance of  milky  juice. 


14     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

To  be  sure  rubber  plants  grow  most  luxuriously 
where  the  soil  is  exposed  to  inundations  or  regular 
periods  of  rain.  In  a  very  wet  season  the  milky 
juice  is  watery,  and  contains  but  little  rubber,  while 
in  dry  seasons  the  content  of  rubber  is  greater,  but 
the  quantity  of  milky  juice  less,  and  the  work  of 
obtaining  the  juice  is  more  difficult.  The  content 
of  rubber  in  the  latex  varies  between  15  and  40  per 
cent.  With  a  content  of  less  than  15  per  cent.,  the 
work  of  gathering  the  latex  is  not  remunerative. 

Cultivation. 

\ 

It  is  obvious  that  in  view7  of  the  growing  import- 
ance of  the  rubber  industry,  attempts  should  have 
been  made  to  acclimatize  the  rubber  plants  in  other 
than  their  native  countries.  England  took  the 
initiatory  steps  in  this  direction,  and  experiments 
were  made  to  acclimatize  in  her  Asiatic  colonies 
such  varieties  of  plants  as  might  prove  suitable  to 
the  soil  and  climate,  India  being  selected  as  the 
most  promising  field.  The  first  experiments  with 
an  enclosed  plantation  were  made  in  1860  with  the 
native  jffy'c?/s,  which  produces  a  remunerative  yield 
only  after  a  growth  of  '25  years,  and  can  be  tapped 
only  every  three  years.  When  fifty  years  old  the 
Ficus  tree  yields  every  three  years  about  45  pounds 
of  rubber. 

This  calculation,  and  especially  the  long  time  re- 
quired before  (he  tree  becomes  remunerative,  did  not 
hold  out  sufficient  inducements;  and  besides,  tests 
made  in  the  meanwhile  showed  that  the  rubber  ob- 


RAW    MATERIAL.  15 

tained  was  of  inferior  quality  to  that  of  Para  and 
( Vara.  Hence  the  further  cultivation  of  this  variety 
was  discontinued. 

Consideration  was  also  given  to  the  introduction 
of  Urceola  elastica,  which  yields  the  first  crop  in  its 
third  year,  and  to  Urceolaesculenta,  which  from  its 
seventh  year  on  yields  one  to  four  pounds  of  rubber, 
but  it  was  claimed  that  Castilloa  elastica  would 
prove  most  remunerative,  though  its  rubber  is  not 
of  the  first  quality.  In  1875,  the  administration  of 
the  Kew  Botanical  Garden  authorized  Robert  Cross, 
a  distinguished  botanist  and  gardener,  to  make  a 
journey  to  Central  America  for  the  purpose  of  study- 
ing the  different  varieties  of  Castilloa,  with  a  view 
of  introducing  them  in  the  English  colonies.  How- 
ever, the  plant,  which  flourished  in  the  Kew  hot- 
houses in  the  hands  of  skilled  gardeners,  died  in  the 
open  air,  the  moist  climate  of  its  native  country 
where  it  rains  nine  months  in  the  year  being  want- 
ing. 

In  1876,  Cross  was  again  commissioned  to  bring 
young  plants  of  Hevea  brasiliensis  from  the  plains 
of  the  Amazon  river.  Though  the  natives  jealously 
guard  the  trees  in  order  to  retain  a  monopoly  of 
such  an  important  industrial  plant,  Cross  succeeded 
in  shipping  a  number  of  Hevea  to  Kew.  The  result, 
however,  was  the  same  as  with  Castilloa.  The  tree 
to  be  sure  grew  in  various  kinds  of  soil,  but  reached 
luxuriant  development  only  on  the  banks  of  run- 
ning streams  where  a  moist  soil  had  not  degenerated 
into  a  swamp.  On  the  Amazon  river  ten  days 


16     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

seldom  pass  by  without  rain,  and  every  morning 
the  trees  are  enveloped  in  a  heavy  dew.  The 
southern  portion  of  Burma  alone  offers  a  climate 
approximately  like  it. 

Beside  the  difficulties  growing  out  of  climatic 
differences,  another  important  point  had  been  left 
out  of  consideration  in  making  these  experiments. 
A  country  for  the  introduction  of  a  rational  cultiva- 
tion of  rubber  trees  to  be  carried  on  in  an  orderly 
manner,  must  be  habitable,  so  that  people  can  live 
there  and  stand  continual,  regular  work.  The 
territory  of  Assam  which  was  selected  for  the  ex- 
periments is  just  as  little  suited  for  habitation  as  the 
native  country  of  Castillio  and  Hevea,  the  regions 
of  the  Amazon  and  of  the  San  Juan,  which  only  the 
Seringueiros,  as  the  rubber  gatherers  are  called,  can 
penetrate  during  the  so-called  dry  season,  and 
where,  exposed  to  fever  and  tormented  by  insects, 
they  work  and  impatiently  await  the  end  of  the 
harvest.  These  are  the  principal  reasons  which 
rendered  a  rational  culture  of  these  two  trees  im- 
possible not  only  in  India  but  also  in  America. 

Acclimatizing  experiments  with  Manihot  glaziovii 
which  yields  the  Ceara  rubber  were  more  successful. 
It  requires  a  stony  soil,  and  though  it  demands  moist- 
ure, can  stand  great  drought.  Its  habitat  is  the  most 
mountainous  and  the  roughest  regions  of  Brazil, 
where  a  temperature  of  77°  to  86°  F.  prevails.  It 
flourishes  at  a  height  of  6,000  feet  above  the  *ea,  re- 
quires no  special  care,  and  readily  adapts  itself  to 
the  climatic  conditions  of  its  adopted  country. 


RAW    MATERIAL.  17 

The  seed  coat  is  of  remarkable  thickness,  and  very 
hard,  and  the  natural  process  of  germination  occu- 
pies, it  is  said,  more  than  a  year.  All  that  is  neces- 
sary to  hasten  this,  is  to  assist  the  seed  coat  in  split- 
ting, which  is  best  effected  by  holding  the  seed 
firmly  and  rasping  off  with  a  file  both  edges  at  the 
radicular  end,  recognized  externally  by  possessing 
at  its  side  a  flat  two-lobed  appendage,  technically 
known  as  the  caruncle.  It  is  best  not  to  file  off  the 
actual  end,  as  the  radicle  of  the  embryo  may  then 
be  injured.  After  this  treatment  properly  per- 
formed, the  young  plant  appears  above  ground  in 
two  or  three  weeks.  The  seedlings  require  no  par- 
ticular attention.  They  grow  rapidly  and  may  be 
finally  planted  out  at  distances  of  20  feet.  Planta- 
tions may  also  be  formed  by  cuttings,  which  take 
root  as  easily  as  a  willow.  They  should  be  from 
the  points  of  strong  shoots,  and  about  one  foot  in 
length.  In  planting,  each  shoot  may  be  put  down 
in  the  soil  to  a  depth  of  six  inches.  On  loose,  sandy 
soil,  or  exhausted  coffee  land,  plantations  may  be 
formed  at  little  expense.  Hard,  diy  gravelly  wastes, 
if  found  to  support  any  kind  of  bush,  are  also  suit- 
able sites.  In  strong  land,  holes  may  be  made  with 
an  iron  jumper,  and  a  stout  cutting  put  into  each, 
and  filled  with  pebbles.  On  bare  or  thinly  covered 
portions  of  rock,  the  cuttings  might  be  laid  down 
flat,  and  a  little  heap  of  stones,  or  any  kind  of 
debris,  about  the  size  of  a  mole-hill,  piled  over  each, 
care  being  taken  that  the  extreme  point  of  each 
cutting  with  a  bud  is  left  uncovered. 
2 


18     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

The  habits  of  Manihot  pointed  it  out  as  being 
well  adapted  for  cultivation  in  Ceylon,  and  atten- 
tion was  concentrated  on  it  as  being  the  quickest 
growing,  and  promising  not  only  early,  but  hand- 
some returns.  Several  plantations- were  started  in 
the  Dumbara  valley,  and  the  returns  of  rubber 
were  said  to  be  profitable  until  it  was  found  that 
the  trees  and  their  shade  were  inimical  to  the  more 
important  cacao  trees  underneath.  According  to 
the  latest  reports,  the  culture  of  Manihot  glaziovii 
has  been  abandoned  in  the  Java  Botanical  Gardens 
because  "  the  promised  magnificent  results  have  in 
no  respect  been  fulfilled." 

According  to  a  circular  issued  from  the  Royal 
Botanic  Gardens,  Peradeniya,  by  the  Director,  Mr. 
J.  C.  Willis,  January  27,  1898,  the  only  important 
rubber  at  the  moment  in  Ceylon  is  the  Para  kind. 
The  tree  is  well  suited  to  the  climate  of  the  low 
country  in  the  southwest  of  Ceylon,  is  readily  culti- 
vated, and  gives  a  fair  yield  of  rubber.  Hevea 
brasiliensis,  the  botanical  name  of  the  Para  rubber 
tree,  forms  a  moderately  tall  tree,  not  much 
branched.  The  seed  is  very  large,  weighing  about 
half  an  ounce.  It  has  a  hard  seed  coat,  and  the 
interior  substance  is  very  oily.  The  seed  soon  loses 
its  power  of  germination,  and  ought  to  be  .sown 
within  a  week  of  its  falling  from  the  tree.  Germina- 
tion takes  place  very  rapidly,  and  a  long  tap  root  is 
soon  produced.  The  seed  should  be  sown  about  an 
inch  deep  in  well  prepared  soil,  in  nurseries,  or,  if 
preferred,  in  bamboo  pots  or  baskets.  They  should 


RAW    MATERIAL.  19 

be  kept  shaded  and  watered,  and  when  the  young 
plants  are  from  18  to  24  inches  high,  they  may  be 
planted  out.  Good  results  are  also  obtained  by 
stumping,  the  plants  being  allowed  to.  grow  about 
three  feet  high,  then  taken  up,  and  the  main  root 
cut  across  about  a  foot  below  the  ground,  but  the 
method  of  planting  out  the  smaller  seedlings  is  per- 
haps preferable. 

The  plant  may  also  be  propagated  by  cuttings. 
The  method  employed  in  the  Botanical  Gardens  has 
usually  been  to  take  cuttings  near  the  ends  of  the 
branches,  but  further  back  than  any  of  the  leaves. 
Each  cutting  is  about  a  foot  long,  and  as  thick  as  a 
lead  pencil,  and  is  cut  off  at  both  ends  by  oblique 
cuts  made  just  below  leaf  scars.  This  method  is  some- 
what precarious ;  sometimes  nearly  all  the  cuttings 
grow,  at  other  times  only  a  small  proportion. 

The  seedlings,  stumps  or  cuttings  should  be 
planted  out  during  rainy  weather  in  prepared 
places.  Holes  should  be  dug  and  filled  with  good 
soil,  a  little  manure  being  often  of  advantage.  The 
young  plants  require  to  be  lightly  shaded  for  a  time 
until  they  are  established,  and  probably  for  the  first 
two  or  three  years  they  will  grow  the  better  for  a 
certain  amount  of  shade,  such  as  would  be  given  by 
narrow  belts  of  trees  running  through  the  planta- 
tion. These  belts  should  be  arranged  to  act  as  wind 
belts,  as  the  Hevea  is  easily  injured  by  wind.  By 
the  time  the  trees  are  about  three  years  old,  they 
will  have  grown  up  to  a  height  of  about  25  or  30 
feet,  and  form  their  own  shade.  Various  distances 


20     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

apart  have  been  tried  in  planting  Hevea,  but  the 
best  results  have  been  obtained  by  planting  eight  or 
ten  feet  apart  each  way.  Hevea  is  a  surface-feeding 
tree,  and  catch  crops  should  not  therefore  be  grown 
between  the  trees,  which  require  all  the  nourish- 
ment that  the  soil  can  afford.  Weeding  is  also  re- 
quired the  first  year  or  two,  but  afterwards  the  trees 
form  a  dense  shade  under  which  but  'few  weeds 
grow. 

The  yield  of  rubber  from  very  young  or  slender 
trees  is  too  small  to  make  their  tapping  worth 
while,  and  it  is  best  for  many  reasons  to  abstain 
from  tapping  a  tree  until  it  has  reached  a  girth  of 
two  feet.  In  a  large  plantation  the  girth  of  the 
trees  always  varies  between  wide  limits.  A  few 
trees  may  be  fit  to  tap  after  the  sixth  year,  and  in 
every  subsequent  year  more  and  more  trees  will 
reach  the  size  necessary.  In  favorable  localities  the 
bulk  of  the  trees  should  be  in  bearing  before  the  end 
of  the  eleventh  year. 

Experiments  in  the  rational  cultivation  of  rubber 
trees  were  also  made  in  other  countries,  especially 
in  the  French  colonies,  for  instance,  on  the  Congo. 
In  consequence  of  the  irrational  manner  in  which 
the  natives  treated  the  indigenous  rubber  plant, 
Landolphia,  it  wras  feared  that  in  time  it  would 
entirely  die  out.  E.  Pierre,  the  creator  of  the  botan- 
ical garden  at  Libreville,  endeavored  to  prevent  this 
danger  by  the  acclimatization  of  foreign  plants,  and 
he  also  selected  the  Manihot  as  had  been  done  in 
Ceylon.  It  would  seem  that  the  experiment  has 


RAW    MATERIAL.  21 

been  successful,  Pierre  reporting  in  regard  to  it  as 
follows:  "A  single  tree  which  I  planted  in  1887 
has  furnished  up  to  the  present  time  (1898)  115 
trees.  The  .plant,  which  M.  de  Brazza  has  endeav- 
ored to  introduce  as  much  as  possible  among  the 
natives,  has  a  great  future  for  this  country.  The 
tree  .introduced  in  1887  has  already  yielded  14,000 
to  15,000  young  plants,  of  which  several  thousand 
have  been  delivered  to  the  natives  in  the  remotest 
parts  of  the  Congo  territory." 

The  director  of  the  garden  at  Libreville  hopes  to 
be  able  to  distribute  in  a  short  time  more  than 
200,000  young  shoots  for  stocking  new  plantations. 

On  the  other  hand,  a  young  French  colonist,  who 
has  for  some  years  resided  in  the  interior,  in 
X'Djole  on  the  Ogooue  writes  as  follows :  "  It  is 
true  that  the  Pahouins  have  been  furnished  with 
young  manihot  plants,  and  explicit  instructions 
regarding  their  cultivation  have  been  given.  But 
in  most  cases  the  natives  have  thrown  away  the 
shoots,  and  when  not  watched,  continue  in  their 
barbaric  destruction  of  the  rubber  trees.  Why,  if 
by  penetrating  a  short  distance  into  the  interior 
the}-  are  assured  of  an  easy  and  rich  crop,  should 
they  undertake  the  laborious  task  of  stocking  a 
plantation,  and  wait  for  years  for  a  crop  which  they 
may  not  live  to  gather  and  enjoy  the  benefits  of? 
Hence  it  is  not  sufficient  to  lay  out  plantations  and 
hand  over  the  young  trees  to  the  natives.  The  care 
of  these  plants  must  be  entrusted  to  the  colonists  in 
order  to  obtain  favorable  results." 


22  INDIA    RUBBER,  GUTfA    PERCHA,  BALATA. 

According  to  Paroisse  the  Manihot  cultivated  in 
Libreville  is  not  the  one  planted  in  Ceara  and  Cey- 
lon, but  a  variety  indigenous  to  an  island  on  the 
south  coast. 

Acclimatizing  experiments  have  also  been  made 
in  Coch in-China,  where  the  soil  and  climate  are 
especially  suitable  for  the  cultivation  of  rubber 
plants.  Hevea  gnyanensis  has  been  successfully 
raised  in  the  garden  at  Saigon.  But  whether  this 
enterprise  will  be  crowned  with  better  success  than 
in  the  Kew  garden  remains  to  be  seen.  Experi- 
ments have  also  been  made  in  Reunion. 

Attempts  towards  a  rational  cultivation  of  rubber 
plants  are  now  made  in  Peru,  Columbia,  Costa 
Rica,  Mexico,  and  even  in  the  Amazon  River  dis- 
trict, and  nearly  everywhere  the  success  attained 
corresponds  to  the  efforts  made. 

In  Mexico  a  number  of  enterprising  citizens  are 
deeply  interested  in  the  project  of  starting  rubber 
plantations,  and  as  the  soil  and  climate  of  portions 
of  that  country  are  suitable  for  that  purpose,  there 
is  no  doubt  but  that  their  efforts  will  be  crowned 
with  success. 

Castilloa  elastica  is  indigenous  to  the  Isthmus  of 
Tehuantepec,  and  particularly  to  that  region  lying 
near  the  Trinidad  and  Colorado  rivers  in  the  south- 
eastern portions  of  the  states  of  Vera  Cruz  and 
Oaxaca.  In  these  districts  it  is  found  growing 
under  varying  conditions,  though  with  certain  limi- 
tations, for  example:  from  sea  level  to  an  elevation 
of  1500  feet.  In  some  localities  there  are,  doubt- 


UNIVERSITY) 

RAW    MATERLkPA  ,  23 


less,  exceptions  where  the  tree  may  ascend  the 
mountains  1000  feet  higher.  Careful  observation 
justifies  the  belief  that  the  zone  wherein  the  tree 
attains  its  best  development  lies  between  sea  level 
and  1500  feet  altitude,  and  within  a  virgin  forest 
district,  with  a  mean  annual  temperature  approxi- 
mating 80°  F.  or  a  range  of  from  60°  minimum  to 
9f>°  maximum  ;  also  a  well  distributed  rain  fall  ap- 
proximating 100  inches  per  annum. 

The  trees  are  found  growing  in  various  soils, 
seldom  in  arid,  gravelly  districts,  and  when  so 
found  presenting  a  stunted  appearance.  They  do 
not  occur  in  swampy  or'inundated  districts.  They 
seem  to  prefer  reddish  clay  soil  where  drainage  is 
good,  or  black  or  reddish  sandy  loam.  Occasion- 
ally they  grow  in  rocky  soil  with  deep  deposits  of 
of  leaf  mould,  but  only  where  there  is  much  humid- 
ity and  shade.  They  reach  their  finest  develop- 
ment, however,  in  alluvial  soils  mixed  or  overlaid 
with  dark  forest  loam,  and  in  company  with  a  fine 
growth  of  other  trees,  and  more  especially  when  the 
land  is  somewhat  rolling  in  character,  insuring 
proper  drainage.  In  such  land  the  wrild  trees  exist 
in  greater  number  near  the  sides  of  arroyos  or 
streams,  which  rarely  overflow  their  banks,  though 
the  trees  near  and  on  the  summits  of  these  rolling 
hills  are  quite  as  fine  in  development.  Probably 
the  greater  number  in  the  former  case  is  owing  to 
the  fact  that  the  seeds  falling  from  trees  above,  are 
washed  down  and  find  lodgment  in  the  more  level 
places.  Experiments  in  planting  have  demon- 


24  INDIA    RUBBER,  GUTTA    PERCH  A,  BALATA. 

strated    equally    as   good    growth   away    from   the 
margins  of  streams  as  upon  them. 

The  seed  matures  the  early  part  of  June,  just 
about  the  beginning  of  the  rainy  season,  and  soon 
falls  from  the  trees.  Germination  takes  place  very 
quickly  in  about  ten  days  or  two  weeks.  The 
vitality  of  the  seeds  is  very  short,  and  rnuch  disap- 
pointment will  be  met  with  by  those  planting  seeds 
a  few  months  old.  The  seeds  should  be  gathered 
daily,  when  they  commence  to  ripen,  placed  in  a 
barrel  with  a  gallon  of  water  to  about  a  peck  of 
seeds.  In  eighteen  hours  fermentation  will  have 
sufficiently  loosened  the  pulp,  without  injury  to  the 
germ,  so  that  it  can  be  washed  off.  The  seeds 
should  then  be  laid  upon  mats  in  a  dry,  but  not  too 
sunny  position,  for  not  longer  than  a  week.  They 
are  then  ready  for  planting.  Under  this  plan  90 
per  cent,  of  seedlings  may  be  procured.  If  gathered 
and  allowed  to  remain  in  a  mass  for  a  week  or 
more  with  the  pulp  on  them,  they  generafe  a  fierce 
heat,  which  utterly  destroys  the  germ  ;  while  if 
washed  and  dried,  as  above  stated,  but  not  planted 
for  two  or  three  months,  the  yield  of  seedlings  will 
be  insignificant,  if  not  a  complete  failure.  The 
cotyledons  undergo  a  rapid  chemical  change,  leav- 
ing no  nourishment  for  the  germ.  It  is  thus  easy 
to  see  how  a  whole  season  may  be  lost  in  starting  an 
enterprise  of  this  kind. 

Seeds  planted  in  June  may  be  transplated  the  end 
of  August,  and  attain  a  height  of  three  feet  by  the 
following  June.  From  experiments  made  on.  the 


RAW    MATERIAL.  25 

Isthmus  of  Teh  u  an  tepee,  it  appears  that  the  forest 
system  of  planting  is  more  rational  than  the  com- 
plete clearing  of  the  land  and  planting  in  regular 
orchard  form,  as  it  entails  less  labor  and  expense, 
and  affords  the  natural  conditions  of  partial  shade 
and  a  greater  degree  of  humidity.  These  conditions 
do  appear  to  be  essential  to  the  highest  development 
of  the  tree  and  the  greatest  yield  of  sap.  Hence 
this  system  involves  simply  the  clearing  of  the 
under-growth  and  planting  the  seedlings  at  as 
nearly  uniform  distances  as  the  standing  forest  will 
permit,  only  destroying  such  forest  trees  as  are 
unnecessary  to  the  fulfillment  of  the  demands  of 
shade  and  humidity,  thus  increasing  the  number  of 
rubber  trees  per  acre. 

If,  however,  a  regular  plantation  in  regular 
orchard  form  is  to  be  started,  and  the  land  set  aside 
for  the  purpose  is  covered  with  trees,  these  must  be 
felled,  and  the  under-growth  cleared  only  where  the 
young  trees  are  to  be  planted,  providing  no  side 
planting  is  to  be  made.  This  work  must  be  per- 
formed in  the  months  of  March  and  April,  and  im- 
mediately after  Indian  corn  should  be  sown  in  the 
open  spaces  15  inches  apart.  This  operation  is  simply 
done  by  making  a  hole  in  the  ground,  dropping  in 
a  few  grains,  and  covering  over  with  the  foot. 
Should  the  planter  wish  to  adopt  the  most  economic 
system,  and  thereby  obtain  the  greatest  return  for 
the  money  invested,  it  would  be  advisable  for  him 
to  plant  besides  corn,  cotton,  bananas  and  coffee. 
But  the  attempt  to  plant  Mocha  coffee  must  not  be 


26     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

made  in.  elevations  less  than  1000  feet  above  sea 
level,  neither  on  plains,  nor  where  the  temperature 
exceeds  85°  F. 

In  the  latter  case  the  acreage  to  be  planted  must 
be  stubbed,  and  the  under-brush  forked  in  or  burnt 
before  sowing  the  corn  ;  then  line  and  stake  the 
plot  in  rows  15  feet  apart.  Peons  who  are  posted  in 
this  kind  of  work,  especially  in  coffee  planting,  have 
a  long  cord  or  rope — 24  to  36  varas  *  in  length — on 
which  they  mark  the  divisions  with  inks  made 
from  dye-woods  in  the  forests  in  these  sections.  The 
cord  is  held  by  two  men,  and  another  one  marks 
the  holes  with  his  garrocha,  leaving  a  stake  in  the 
excavated  place  every  15  feet  in  the  row.  The  rule 
of  setting  the  trees  at  such  distance  would  ensure 
larger  size,  and  a  greater  flow  of  sap.  As  to  shade, 
if  the  young  plants  have  been  taken  from  woods 
under  shelter,  then  natural  trees  must  be  left  on  the 
plot  before  clearing  to  protect  them  from  the  strong 
rays  of  the  sun  until  they  are  10  or  12  feet  high, 
and  have  a  prosperous  appearance. 

This  must  not  be  overlooked,  as  the  plant  will 
suffer  a  great  deal  from  transplanting  even  when 
that  operation  is  done  under  the  best  of  circum- 
stances. But  if  the  young  plants  are  obtained  from 
unsheltered  places,  or  from  a  nursery  established  in 
an  open  space,  they  having  grown  stronger  and 
stouter  will  require  no  shelter,  and  will  flourish 
more  rapidly  and  vigorously  than  if  they  had  shade. 

*  1  vara  =  32.9  inches. 


RAW    MATERIAL.  27 

If  the  seedlings  or  cuttings  can  be  obtained  within 
a  few  miles  from  a  plot,  it  is  advisable  even  to  pay 
as  much  as  $2.50  per  100  than  to  wait  12  months 
for  the  seed  to  grow  in  the  nursery.  When  the 
place  where  the  supply  of  young  plants  or  cuttings 
is  to  be  had  is  too  distant,  the  expense  of  transpor- 
tation would  be  enormous,  and  they  would  suffer  to 
such  an  extent  as  to  render  them  unfit  and  risky 
for  transplanting.  The  only  practical  method  in 
that  case  is  to  start  a  nursery.  For  this  purpose  a 
rich  sandy  loam  should  be  selected.  Beds  are  made 
6  feet  wide  by  15  to  20  feet  in  length,  leaving  a 
walk  2  or  3  feet  wide.  The  seeds  are  sown  8  inches 
apart  in  rows  10  inches  distant  one  from  another. 
This  operation  is  done  in  the  beginning  of  June  or 
a  few  days  after  the  rains  have  started,  and  by 
merely  marking  the  ground,  about  an  inch  deep, 
with  a  stick,  dropping  the  seed  in,  and  covering  it 
with  vegetable  mould. 

In  12  months  the  seedlings  are  about  24  inches 
high  and  ready  for  transplanting.  All  weeds  and 
grass  must  be  carefully  removed  with  the  hand 
from  the  bed  as  they  appear,  and  the  earth  watered 
when  it  seems  dry,  which  is  best  done  in  the  after- 
noon. 

In  the  latter  part  of  May  or  in  the  first  days  of 
June,  when  the  rainy  season  commences,  the  seed- 
lings, young  plants  or  cuttings,  are  transplanted  in 
the  cleared  plot  between  the  corn  and  cotton,  15 
feet  each  way.  In  removing  the  seedling  or  young 
plant,  as  much  of  the  original  soil  as  possible  should 


28  INDIA    RUBBER,  GUTTA    PERCH  A,  BALATA. 

be  left  attached  to  it.  The  earth  must  be  opened 
sufficiently  to  place  the  plant  at  the  same  depth  as 
in  the  seed  bed,  and  then  press  down  the  earth  with 
a  spade  so  as  not  to  allow  an}7  hollows  around  the 
tree.  The  plot  planted  with  rubber  trees  should  be 
inspected  now  and  then  in  order  to  judge  how  they 
are  progressing,  and  to  replace  the  plants  that  have 
withered  and  died.  In  July  or  August  it  will  be 
necessary  to  clean  the  corn,  weed  the  plot,  and  after 
harvesting  the  corn,  banana  suckers  (hijos)  can  be 
planted  7  feet  apart  between  the  rows  of  rubber 
trees. 

In  Chiapas  and  Tabasco,  cacao  trees  are  set  a  few 
feet  from  the  2  or  3-year-old  rubber  trees,  the  latter 
acting  as  shade  for  the  former  in  lieu  of  the  regular 
rnadre  protector  or  shade  tree.  Vanilla  trees  can  be 
attached  to  the  cacao  tree,  and  by  that  means,  after 
the  lapse  of  6  or  7  years,  the  planter  has  three  or  four 
different  crops  to  harvest.  Furthermore,  bees  could 
be  raised  on  the  place  which  would  act  ^s  a  medium 
to  fertilize  the  vanilla  flowers,  and  give  a  hand- 
some profit  from  honey  and  beeswax.  Again, 
should  the  proprietor  not  want  ajiy  side  planting, 
cattle,  which  bring  a  good  income  in  those  sections, 
may  be  permitted  to  graze  on  the  land  as  soon  as 
the  young  trees  are  well  rooted  and  have  grown 
over  20  feet  in  height.  After  going  through  the 
work  of  transplanting,  the  only  care  in  the  cultiva- 
tion of  the  tree,  thereafter,  is  that  of  keeping  the 
ground  free  from  all  weeds  and  the  rank  vegetation 
of  the  tropics. 


I;A\V  MATERIAL.  29 

It  is  difficult  to  give  the  cost  of  establishing  a 
rubber  plantation,  but  it  has  been  estimated  that 
the  entire  expense  for  a  plantation  of  100,000  trees 
will  not  exceed  25,000  dollars  Mexican  currency. 

Manner  of  obtaining  Crude  Rubber. 

The  quality  of  the  crude  rubber  depends  largely 
on  the  method  employed  in  obtaining  the  latex,  and 
the  manner  in  which  the  rubber  is  separated  from 
it.  There  are  two  methods  of  obtaining  the  milky 
juice,  namely  : 

1.  By  cutting  down  the  trees. 

2.  By  tapping  the  trees  by  making  incisions  in 
the  bark. 

The  first  method — cutting  down  the  trees — is  still 
employed  in  Africa  and  Asia,  and  especially  in  the 
Indian  Archipelago,  where,  within  a  few  years,  the 
Borneo  rubber  was  only  obtained  in  this  manner. 
Generally  speaking,  this  method  must  be  condemned 
as  irrational  and  destructive,  though  it  might  be 
permissible  if  the  plants  die  anyhow  in  conse- 
quence of  tapping,  and  in  the  case  of  trees  which 
have  to  be  removed  in  thinning  out  primitive 
forests.  It  is  asserted  by  the  natives  of  Peru  that 
Il'iiicornia  speciosa  dies  in  consequence  of  insects 
attacking  the  places  where  the  incisions  have  been 
made.  On  the  other  hand,  by  cutting  down  the 
tree  just  above  the  ground,  the  stump  soon  sprouts 
again  and  throws  out  new  shoots,  so  that  in  a  few 
years  there  will  be  a  group  of  trees  where  formerly 
was  but  a  single  tree. 


30     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

Cutting  down  the  trees  for  the  purpose  of  thinning 
primitive  forests  is  permissible  if  carried  out  in  mod- 
eration and  with  judgment,  it  being  useful,  for  in- 
stance, in  the  dense  forests  of  Africa,  since  by  the 
admission  of  air  and  light  a  more  vigorous  growth 
is  promoted. 

However,  tapping  by  making  incisions  is  the 
most  rational  manner  of  obtaining  the  sap,  but  care 
must  be  exercised  to  prevent  injur}7  to  the  trees. 
The  method  of  tapping  at  present  employed  on  the 
lower  Amazon  river  is  decidedly  the  best  and  most 
practical.  The  operation  is  as  follows  : 

The  Seringueiro,  or  as  he  is  frequently  called, 
the  Cauchero,  begins  to  work  immediately  at  day- 
break, or  as  soon  as  he  can  see  to  move  among  the 
trees.  His  tools  consist  of  a  machado — a  small  axe 
with  a  short  handle  and  an  edge  a  little  over  an 
inch  wide — further  a  bucket  and  a  number  of  small 
tin  cups  slightly  concave  on  one  side  in  order  to  fit 
the  convexity  of  the  tree  trunk. 

The  trunk  of  the  tree  having  been  carefully 
cleansed,  and  the  ground  around  the  tree  swept, 
the  collector  takes  the  axe  in  his  right  hand  and, 
striking  in  an  upward  direction  as  high  as  he  can 
reach,  makes  a  deep  upward  sloping  cut  across  the 
trunk,  which  always  goes  through  the  bark  and 
penetrates  an  inch  or  more  into  the  wood.  The 
cut  is  an  inch  in  breadth.  In  this  manner  each 
tree  is  tapped  in  twelve  places.  Some  of  the  col- 
lectors arrange  the  incisions  in  the  form  of  a  V, 
and  others  in  spirals,  while  others  again  simply 


RAW    MATERIAL.  31 

make  them  vertically,  one  above  the  other,  from  a 
point  up  to  which  they  can  reach  with  the  hand 
down  to  a  few  -inches  above  the  ground. 

The  incisions  having  been  made,  the  tin  cups  are 
fastened  to  the  tree  with  a  piece  of  kneaded  clay, 
of  which  the  Seringueiro  carries  a  supply  in  his 
bag.  One  man  is  apportioned  to  a  path  or  district 
containing  100  trees.  When  he  has  tapped  and 
cupped  his  trees,  he  sits  dowai  at  the  end  of  the  path 
for  half  an  hour  or  so.  As  soon  as  he  perceives 
that  the  tree  last  tapped  has  ceased  to  drip  the 
milk,  he  starts  at  a  trot  on  the  back  track,  detach- 
ing and  emptying  the  cups  into  his  calabash  as 
quickly  as  possible.  The  cups  he  leaves  upside 
down  at  the  base  of  the  tree.  Speed  throughout  is 
a  great  object,  as  the  milk  speedily  coagulates.  The 
quantity  of  milky  juice  obtained  varies  according  to 
whether  the  tree  is  vigorous  or  decaying,  but  at  an 
average  each  incision  yields  in  one  to  three  hours 
about  0.21 1  gill.  The  yield  is,  however,  not  the  same 
every  year,  it  being  influenced  by  long  continued 
rain  and  extraordinary  drought,  [is  well  as  by  the 
incisions  having  been  made  either  upon  the  sunny 
or  shady  side  of  the  trunk.  The  latter  circum- 
stance explains  the  fact  why  some  natives  prefer 
tapping  at  nightfall.  Besides,  the  natives  assert 
that  the  milky  juice  is  more  abundant  during  full 
moon  than  at  any  other  time. 

The  quantity  of  sap  obtained  from  each  tapping 
of  150  trees  amounts  to  about  52  quarts  of  milky 
juice,  or  about  80  pounds  of  crude  rubber.  By 


32     INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

counting  upon  20  tappings  each  year,  the  yield 
would  represent  a  product  of  about  1600  pounds  of 
crude  rubber. 

On  the  Upper  Amazon  tapping  is  effected  in  a 
similar  manner,  but  the  work  is  done  less  carefully, 
and  the  tools  used  are* of  a  more  primitive  char- 
acter. The  further  the  collector  penetrates  into  the 
virgin  forest,  the  less  baggage  he  wants  to  carry.  A 
shell  answers  for  a  cup,  and  for  the  small  machado 
the  old-fashioned  broad  hatchet  is  substituted  which 
has  proved  so  destructive  to  the  rubber  trees. 

With  slight  deviations,  the  method  of  tapping  is 
the  same  throughout  South  America,  The  arrange- 
ment, number  and  depth  of  the  incisions  may  vary, 
as  well  as  the  mode  of  harvesting,  but  the  principle 
is  the  same. 

In  Central  America,  where  Castilloa  elastica  is  the 
principal  rubber  tree,  a  different  treatment  is  re- 
quired. The  incision  is  replaced  by  a  puncture, 
and  is  made  with  a  smaller  and  finer  tool  than  the 
machado. 

In  Africa,  the  operation  of  tapping  is  still  carried 
on  in  an  imperfect  and  irrational  manner,  almost 
every  region  having  its  own  method.  As  a  rule, 
the  incisions  are  cut  too  deep,  and  in  consequence 
of  this  the  latex  is  mixed  with  other  juices,  which 
impairs  the  quality  of  the  rubber,  and  the  African 
product,  which  is  naturally  inferior  to  the  South 
American,  and  especially  to  the  Amazon  rubber, 
becomes  thereby  of  still  less  value. 

In  Asia,  especially  in  the  regions  where  the  rub- 


RAW    MATERIAL.  33 

ber  is  obtained  from  the  different  varieties  of  Ficus, 
incisions  of  an  elliptic  shape  extending  to  the  inner 
bark  or  bast  are  made  in  the  lower  portion  of  the 
trunk  and  in  the  aerial  roots.  The  yield  of  latex 
depends  on  the  season  of  the  year.  While  the 
quantity  obtained  in  February  and  March  is  small, 
the  content  of  rubber  is  considerable,  and  for  this 
reason  tapping  during  these  months  is  most  remun- 
erative. The  conditions  are  similar  in  August,  when 
the  content  of  rubber  in  the  latex  is  30  per  cent., 
while  in  other  months  it  decreases  to  10  per  cent. 

In  Australia  the  methods  in  use  are  generally  the 
same  for  trees  of  a  similar  nature  as  in  Asia,  but  the 
destructive  method  of  felling  the  trees  is  also  in 
vogue,  especially  where  through  the  carelessness 
and  shortsightedness  of  the  authorities  the  matter  is 
left  to  the  natives  themselves.  Urceola  elastica  is 
especially  subject  to  such  thoughtless  destruction. 
The  stem  of  this  climbing  plant  is  cut  up  and  the 
pieces  are  laid  over  large  vessels  for  the  sap  to 
exude,  and  when  the  flow  becomes  slow,  it  is 
assisted  by  a  brushwood  fire. 

Coagulation  of  the  Latex. 

The  latex  obtained  by  cutting  down  or  by  tap- 
ping the  plants  separates  the  rubber  contained  in  it 
only  when  subjected  to  a  particular  method  of  coag- 
ulation which  varies  in  every  country,  nay,  in 
every  province,  and  even  from  one  side  of  a  river 
to  the  other.  Hence  it  frequently  happens  that 
there  is  a  great  variation  in  the  quality  of  rubber 
3 


34     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

obtained  from  the  same  plant  and  in  the  same 
country,  according  to  the  coagulating  process  in  use. 
Dr.  F.  von  Hoehnel  and  James  Collins  have  de- 
scribed the  various  methods  of  coagulation  actually 
in  use,  and  the  following  summary  showing  the 
various  methods,  and  the  countries  in  which  they 
are  employed,  is  based  upon  their  researches  : 
The  coagulation  of  the  latex  is  effected  : 

I.  By  heat. 

1.  By  artificial  heat : 

a.  Dry  heat  or  fumigation  on  the  Amazon,  in 
New  Caledonia. 

b.  Moist  heat,  in  Mexico,  Central  America. 

2.  By  natural  heat : 

a.  Separation   of  the  serum  by  means  of  the 
soil,  in  Angola  (Lower  Guiana). 

b.  Separation  of  the  serum  by  means  of  the 
human  bod}7,  in  Congo  ;  Angola. 

c.  Evaporation  upon  even  surfaces,  in  Ceara ; 
Angola. 

II.  By  skimming : 

3.  By    skimming   after   increasing   the   fluid  to 
double  its  quantity  by  the  addition  of  water,  in 
Bahia. 

4.  Skimming  after  a  period  of  rest,  addition  of 
four  to  five  parts  of  water,  draining,  washing 
and  pressing,  in  Bahia  ;  Congo. 

III.  By  disintegration  : 

5.  Chemical  disintegration  by  means  of  reagents, 
Matto  Grosso  (interior  of  Brazil) ;  Pernambuco  ; 
Maranham. 


RAW    MATERIAL.  35 

6.  Chemical  disintegration  by  the  use  of  plants 
as  reagents,  in  Peru  ;  Guatemala  ;  Nicaragua ; 
Gambia  ;  Madagascar  ;  Casamanza. 
IV.  By  natural  or  artificial   heat  in   combination 
with  chemical  disintegration,  in  Gambia ;  Sene- 
gal ;    Madagascar ;  Casamanza. 
A  brief  description   of  the  various  processes  of 
coagulation  may  be  of  interest. 

Coagulation  by  artificial  dry  heat  or  fumigation. 
This  method  is  especially  suitable  for  the  latex  of 
Hevea  and  Micranda,  and  is  chiefly  employed  on  the 
Amazon  in  the  preparation  of  Para  rubber,  which 
on  account  of  its  purit}7,  durability  and  elasticity  is 
highly  prized  and  considered  the  best  quality.  This 
method,  which  is  decidedly  the  best,  however,  is  also 
employed  in  other  parts  of  Brazil,  as  well  as  in 
Venezuela  and  Guiana,  and  is  as  follows  : 

The  Seringueiro  or  rubber  gatherer  carefully  re- 
moves from  the  tapped  tree  one  cup  after  the  other 
and  empties  the  latex  into  a  bucket  or  large  bottle- 
gourd,  which  is  covered  with  a  wide-meshed  net  and 
provided  with  a  rope  handle.  The  empty  cup  is 
then  again  secured  under  the  incision,  which,  how- 
ever, is  first  carefully  examined  and  opened  if,  as  is 
frequently  the  case,  it  has  been  closed  by  the  coagu- 
lation of  latex.  The  thin  skin  of  coagulated  latex 
is  removed  from  the  incision  and  carefully  laid 
aside.  The  sap  from  two  or  three  trees  will  fill  the 
bucket.  If  the  hut  of  the  Seringueiro  is  in  the 
immediate  neighborhood  of  the  trees,  the  entire 
yield  of  latex  is  emptied  without  special  care  into  a 


36     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

large  tub ;  but  if  the  Seringueiro  has  to  traverse  a 
considerable  distance  before  reaching  his  domicile, 
3  per  cent,  of  liquid  ammonia  is  added  to  the  latex 
to  prevent  coagulation  on  the  road.  The  actual 
preparation  of  rubber,  that  is,  fumigation,  com- 
mences only  when  all  the  latex  has  been  collected. 
For  this  purpose  a  fire  of  brush-wood  is  kindled, 
and  on  this  a  narrow  funnel-shaped  pot  of  clay, 
called  fumeiro,  is  placed.  When  the  smoke  is  of 
sufficient  density,  which  the  Seringueiro  tests  with 
his  hand,  palm  nuts  are  thrown  upon  the  fire,  the 
nuts  used  being  the  fruits  of  the  Urucury  and 
Uauassu  palms  (Attalea  excelsa  and  Monicaria 
saxifera)  which,  as  a  rule,  can  be  had  in  the  imme- 
diate neighborhood  of  where  the  work  is  carried  on. 
However,  nuts  for  the  creation  of  smoke  are  only 
used  on  the  Lower  Amazon,  where  the  best  rubber 
is  prepared,  the  smoke  of  brush-wood  being  con- 
sidered sufficient  in  other  regions. 

When  the  smoke  is  of  sufficient  density,  the 
Seringueiro,  with  the  bucket  of  milky  juice  by  his 
side,  seats  himself  before  the  fire,  clips  a  club-shaped 
piece  of  wood  with  a  flattened  clay  mould  at  the 
end  into  the  milk  and  turns  the  juicy  end  round 
and  round  in  the  smoke  issuing  from  the  pot.  In 
half  a  minute  the  milk  is  changed  into  a  skin  of 
reddish  tint.  When  tins  is  firm  the  stick  is  again 
dipped  into  the  milk,  and  so  the  process  goes  on, 
layer  being  added  to  layer,  until  a  sufficient  thick- 
ness has  been  obtained.  Another  stick  is  then 
taken  up,  and  the  work  goes  on  until  the  juice  lias 


RAW   MATERIAL.  37 

been  exhausted.  A  good  workman  can  in  this 
manner  prepare  in  one  hour  five  or  six  pounds  of 
rubber.  When  the  cakes  are  completed  they  are 
slit  up  with  a  sharp,  wetted  knife,  and  after  being 
hung  in  the  open  air  to  dry  for  a  few  days,  they  are 
ready  for  sale.  The  flat  rounded  Para  rubber  cakes 
made  in  the  manner  described  are  known  in  com- 
merce as  "  biscuits,"  and  command  a  higher  price 
than  any  other  kind  of  rubber. 

The  most  difficult  portion  of  the  process  of  pre- 
paring rubber  according  to  the  method  above  de- 
scribed is  without  doubt  the  operation  of  fumigating. 
In  order  to  understand  thoroughly  the  efficiency 
of  the  process,  a  knowledge  of  the  composition  of  the 
fresh  latex  is  necessary.  The  milky  juice  of  Hevea 
and  Micranda  from  which  Para  rubber  is  prepared 
contains : 

Rubber,     .         .         .         .32    per  cent. 

Organic  substances  subject 
to  putrefaction,  and  min- 
eral substances,  .  .12  per  cent. 

Water,       .         .         .         .     55-56    " 

Liquid   ammonia   (added),     up  to  3   " 

Traces  of  resin. 

To  be  sure  no  other  latex  possesses  such  excel- 
lent qualities,  but  by  taking  into  consideration  the 
care  exercised  in  collecting  the  sap,  and  in  the  sepa- 
rating process  in  order  to  prevent,  on  the  one  hand, 
loss  in  removing  the  watery  constituents,  and,  on 
the  other,  to  render  innoxious  the  substances  pro- 
ducing putrefaction  and  fermentation,  it  will  be 


38     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

evident  that  the  superior  quality  of  the  rubber  pro- 
duced is  more  due  to  the  excellent  treatment  than 
the  quality  of  the  milky  juice. 

The  latex  contains  substances  subject  to  putrefac- 
tion or  fermentation  whch  may  be  fatal  to  the  rub- 
ber. To  render  these  substances  innocuous,  the 
natives  have,  instinctively,  without  any  scientific 
knowledge,  found  the  most  simple  means.  First, 
by  the  repeated  action  of  moderate  heat  the  greater 
portion  of  the  water  contained  in  the  serum  is  re- 
moved, whereby  fermentation  takes  place  almost 
instantaneously,  but  at  the  same  time  the  incomplete 
combustion  of  the  wood  produces  carbon,  which  is 
a  very  effective  antiseptic,  and  cannot  but  exert  a 
beneficial  influence.  Finally,  by  the  combustion  of 
wood  creosote  is  evolved,  which  mixes  with  the 
smoke,  and  has  also  an  antiseptic  effect  upon  the 
nitrogenous  substances.  It  is  not  positively  known 
whether  the  smoke  of  the  palm  nuts  mentioned 
above  contributes  to  this  antiseptic  action,  but  it  is 
alleged  that  its  benefit  consists  in  its  absorption  of 
the  oxidized  resin  of  the  juice,  and  it  is  the  small- 
ness  of  the  quantity  of  this  resinous  body  in  Para 
rubber  that  gives  it  the  highest  value  in  the  markets 
of  the  world. 

In  connection  with  this  an  experiment  may  here 
be  mentioned  which  may  be  considered  an  imitation 
of  the  process  of  coagulation  in  use  on  the  Amazon, 
and  which  has  been  very  successfully  carried  out  by 
Grandjean  and  Waser  in  New  Caledonia  and  the 
Loyalty  Islands.  In  his  work  on  "  The  Coloniza- 


RAW    MATERIAL.  39 

tion  of  the  New  Hebrides"  (Paris,  1895),  Dr. 
Daville  speaks  in  reference  to  this  process  as  follows  : 

"  The  operation  of  tapping  is  very  simple.  Beside 
the  Brazilian  tin  cup,  a  conical  gutter  tapering  to  a 
hollow  prism,  and  provided  on  one  end  with  a  sharp 
blade,  and  on  the  other  with  a  hook,  is  required. 
The  blade  effects  the  incision  in  the  bark  and 
serves  at  the  same  time  for  securing  the  gutter  to 
the  tree.  The  milk}7  juice  exuding  passes  through 
the  gutter  into  the  tin  cup  suspended  to  the  hook. 
It  is  easy  for  the  workman  to  suspend  the  cups  in 
the  morning,  to  empty  them  every  three  or  four 
hours  into  a  larger  vessel,  a  bottle-gourd,  or  still 
better  a  tin  can,  and  to  replace  them  on  the  tree." 

The  further  operations  correspond  to  those  on  the 
Amazon  river  already  described,  and  the  result  is 
an  excellent  and  valuable  quality  of  rubber. 

It  remains  to  mention  a  few  details  of  the  prep- 
aration of  some  kinds  of  Para  rubber  of  less  fine 
quality,  namely,  Para  Grossa,  Para  entrefina  and 
Sernamby  or  Nigger-head. 

From  the  residues  in  the  cups,  or  adhering 
to  the  lips  of  the  incisions,  a  second  quality  of 
rubber  is  prepared  by  throwing  them  together  and 
shaping  into  a  flat  ball.  This  ball  is  from  time  to 
time  dipped  in  fresh  latex,  and  after  each  such 
coating  fumigated  like  fine  Para.  Finally  it  receives 
several  coatings  of  fresh  latex,  so  that  externally  it 
has  the  same  appearance  as  the  best  quality  of  Para. 
However,  this  deception  is  readily  discovered  by 
cutting  into  it  with  a  knife.  This  quality  of  rubber 


40    INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

contains  a  far  greater  quantity  of  water  and  a  consid- 
erable amount  of  nitrogenous  substances  subject  to 
putrefaction,  the  principal  reason  for  this  being  that 
the  skin  of  rubber  taken  from  the  incisions  has  been 
formed  from  the  latex  by  the  influence  of  natural 
heat.  This  process  of  coagulation  will  be  fully  de- 
scribed later  on,  and  will  explain  the  defects  of 
Para  entrefina. 

Finally  all  the  residues  of  less  value  from  fine 
Para  and  Para  entrefina — the  scrapings  from  the 
moulding  sticks,  the  residues  in  and  around  the 
vessels,  etc. — are  kneaded  into  blocks  and  packed 
into  boxes  or  barrels.  The  whole  mass  sticks  to- 
gether, and  acquires  the  shape  of  the  receptacles. 
This  rubber,  which  is,  of  course,  of  little  value,  is 
known  as  Sernamby  or  Nigger-head.  It  is  very 
moist,  frequently  contains  non-coagulated  latex, 
even  vegetable  and  mineral  particles,  and  has  not 
passed  through  an  antiseptic  process. 

Coagulation  of.  the  latex  by  means  of  mo'st  artificial 
heat  or  by  boiling.  This  extremely  primitive  method 
is  employed  by  the  Indians  of  Mexico  for  the  coagu- 
lation of  the  latex  of  Castilloa.  The  latex  obtained 
by  making  an  incision  or  puncture  in  the  plant  is 
collected  in  a  piece  of  bark  or  in  a  pot,  strained,  and 
poured  into  a  kettle  under  which  a  brushwood  fire 
is  lighted.  As  with  animal  milk,  a  layer  of  cream 
is  formed  under  the  influence  of  heat,  which  by 
continued  boiling  becomes  solid,  and  can  be  sepa- 
rated from  the  watery  constituents.  In  this  manner 
pieces  of  rubber  are  obtained  which,  before  they  are 


RAW    MATERIAL.  41 

brought  into  commerce,  are  dried  and  pressed  to 
deprive  them  as  much  as  possible  of  moisture. 

This  process  is  evidently  very  defective.  The 
mass  is  not  sufficiently  boiled  to  destroy  all  sub- 
stances producing  putrefaction  and  fermentation, 
the  product  is  not  subjected  to  sufficiently  strong 
pressure  to  remove  moisture,  and  finally,  notwith- 
standing that  the  latex  is  strained,  the  treatment  is 
not  sufficiently  careful  to  remove  all  vegetable  and 
mineral  impurities.  In  fact,  experience  has  shown 
the  correctness  of  this  assertion,  since  on  examining 
pieces  of  rubber  prepared  by  boiling  the  blackish 
mass  will  be  found  to  be  full  of  bubbles  filled  with 
a  thick,  greenish  liquid  containing  sand  and 
splinters  of  wood.  More  recently  a  better  quality 
of  rubber  also  prepared  from  the  latex  of  Castilloa 
has  been  introduced  from  Mexico.  It  is  of  a  pale 
brown  color,  and  of  an  agreeable  odor,  and  contains 
neither  sand  nor  other  impurities.  It  is  almost  as 
firm  as  Brazil  rubber,  and  the  loss  in  working  it  is 
only  12  to  15  per  cent.  It  has  not  been  possible  to 
ascertain  the  process  by  which  this  variety  is  pre- 
pared, but  it  may  be  assumed  that  the  latex  receives 
an  addition  of  sea-salt.  In  British  India,  the  latex 
is  also  boiled  in  preparing  the  Assam  rubber  ob- 
tained from  Ficus. 

Coagulation  of  the  latex  by  natural  heat.  The  soil 
as  a  means  of  separating  water.  Coagulation  by  nat- 
ural heat  is  chiefly  in  use  in  East  Africa.  Although 
it  is  occasionally  employed  in  other  regions,  it 
would,  however,  appear  that  all  defective  appliances, 


42     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

which  are  the  chief  reasons  of  the  inferior  quality 
of  the  African  product  and  its  low  price,  are  special 
characteristics  of  the  natives  of  Africa,  whose  laziness 
is  perhaps  only  surpassed  by  their  rapacity. 

The  method  employed  by  some  tribes  on  the 
Congo  and  in  Angola,  who  chiefly  tap  Landolphia, 
is,  according  to  Jeannest,  as  follows  : 

The  native  taps  a  tree  without  caring  whether  it 
is  destroyed  thereby  or  not.  The  sap  trickles  down 
the  trunk  of  the  tree  and  falls  upon  the  ground,  the 
latter  not  having  been  even  properly  cleaned.  The 
hot  air  immediately  commences  to  absorb  the  water 
of  the  latex,  so  that  the  latter  is  half  coagulated  be- 
fore it  reaches  the  ground.  The  hot,  dry  ground 
absorbs  the  rest  of  the  liquid,  and  nothing  remains 
for  the  negro  to  do  but  to  lift  up  the  rubber.  It  is 
not  worth  while  to  criticise  such  a  primitive  method. 
However,  the  natives,  instead  of  removing  mineral 
impurities  as  much  as  possible,  add  them  intention- 
ally. Of  course  the  soil,  which  in  this  process  serves 
as  a  filter,  can  only  absorb  the  fluid  from  the  outer 
portions  of  the  mass,  since  a  skin  is  quickly  formed 
upon  the  surface,  which  no  longer  allows  the  serum 
.to  pass  through.  In  consequence  of  this,  nitrogen, 
sugar,  resin,  etc.,  remain  in  the  interior,  the  rubber 
is  soft  and  sticky,  and  possesses  an  abominable  odor, 
which,  however,  shows  itself  only  later  on.  The 
loss  in  washing  these  varieties  of  rubber  in  the 
factory  is  very  great. 

Coagulation  by  natural  heat;  evaporation  upon  the 
human  body.  This  very  original  method  is  also  in 


RAW    MATERIAL.  43 

use  by  the  natives  of  East  Africa,  and  is  decidedly 
preferable  to  the  process  above  described.  On  the 
Congo,  it  is  carried  out,  according  to  R.  V.  Merlon, 
as  follows :  Before  tapping  the  plant,  the  negro 
divests  himself  of  his  very  limited  clothing,  then 
makes  an  incision,  catches  the  latex  in  his  hands, 
and  covers  his  entire  body  with  it.  Covered  with 
this  curious  coating,  he  returns  to  his  domicile.  A 
crust  is  soon  formed,  which  can  be  removed  in 
patches,  and  is  rolled  into  a  ball. 

According  to  Dr.  Welwitsch,  some  tribes  in 
Angola  proceed  in  a  similar  manner.  The  negro 
presses  his  hand  against  the  trunk  of  the  tree  im- 
mediately below  the  incision,  and  allows  the  exud- 
ing milky  juice  fa  run  over  his  arm.  When  the 
coating  is  of  sufficient  thickness  he,  commencing  at 
the  elbow,  draws  the  rubber  off  like  a  glove  and 
rolls  it  up. 

Although  this  method  cannot  be  recommended, 
as  the  substances  producing  putrefaction  are  not  de- 
stroyed, it  has  the  advantage  of  no  foreign  sub- 
stances being  mixed  with  the  latex.  Evaporation 
of  moisture  is  quite  complete,  as  coagulation  takes 
place  in  very  thin,  often  repeated  layers  upon  a 
large  surface,  the  heat  emanating  from  the  human 
body  also  contributing  essentially  towards  that  end. 

Coagulation  by  natural  heat.  Evaporation  upon 
other  even  surfaces  than  the  ground.  This  method  is 
chiefly  in  use  in  Brazil  in  the  preparation  of  Ceara 
rubber  (Ceara  scraps)  which  is  obtained  from  Mani- 
hot  glazowii,  though  the  same  method  is  also  em- 


44    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

ployed  in  several  regions  in  West  Africa  and  on  the 
mainland  of  India. 

In  Ceara  the  operation  is  conducted  as  follows : 
The  tree  is  tapped  when  about  three  years  old,  that 
is,  when  the  trunk  lias  a  diameter  of  about  4J  to  5 
inches.  After  cleaning  the  ground  around  the  tree 
and  spreading  banana  leaves  for  catching  escaping 
milky  juice,  the  Seringueiro  makes  in  different  places 
and  in  various  directions  slits  in  the  bark  from  the 
foot  of  the  tree  up  to  a  height  of  about  five  feet.  The 
latex  of  Manihot  being  of  much  greater  consistency 
than  that  of  Hevea  and  Micranda,  it  exudes  very 
slowly  and  seldom  reaches  the  ground,  most  of  it 
coagulating  in  the  shape  of  long  tears  upon  the  bark 
of  the  tree,  similar  to  resin  on  our  trees.  To  allow 
it  to  dry,  it  is  permitted  to  remain  several  days  on 
the  tree,  when  it  is  taken  off  in  strips,  folded  to- 
gether or  rolled  into  a  ball,  and  without  further 
preparation,  it  is  thus  brought  into  commerce  as 
Ceara  scraps. 

The  rubber  collected  at  the  commencement  of  the 
harvest  is  of  a  blonde  color,  and  represents  the  best 
quality.  The  second  quality  is  of  a  darker  brown 
color,  and  is  gathered  when  the  rainy  season  begins. 
The  rubber  collected  at  the  foot  of  the  tree  consti- 
tutes the  third  quality,  and  is  mixed,  partly  acci- 
identally  and  partly  intentionally,  with  earth  and 
;sand.  The  loss  in  working  it  frequently  amounts  to 
Wore  than  50  per  cent. 

It  is  scarcely  to  be  wondered  at  that  rubber  thus 
prepared  contains  a  considerable  quantity  of  min- 


RAW    MATERIAL.  45 

era!  and  vegetable  constituents  which  considerably 
decrease  its  value.  Ceara  rubber  has  a  beautiful 
amber  color  and  is  nearly  transparent.  The  latter 
remarkable  property,  which,  according  to  Morellet, 
is  not  possessed  by  any  other  variety  of  rubber,  is 
claimed  to  be  due  to  numerous  holes  in  the  interior 
of  the  mass  through  which  the  rays  of  light  refract. 
Ceara  rubber  has  a  strong  odor,  which  becomes 
decidedly  disagreeable  on  exposing  the  product  to 
moist  heat.  The  pure  article  gives  in  working  75 
to  80  per  cent,  of  rubber,  and  is  quite  resistant. 
There  would  be  a  larger  demand  for  Ceara  rubber 
if  it  were  prepared  with  greater  care  and  not  adul- 
terated by  the  addition  of  earth  and  other  sub- 
stances. The  latex  of  Manihot  is  at  least  equal  to, 
and  perhaps  superior  to  that  of  Hevea,  as  it  contains 
fewer  nitrogenous  substances  which  produce  fermen- 
tation, and  considerably  less  water.  However,  the 
industrial  result  of  pure  rubber  is  only  75  to  80  per 
cent.  Furthermore,  Ceara  scraps  are  difficult  to 
keep,  as  in  consequence  of  their  content  of  sub- 
stances producing  putrefaction  they  require  to  be 
stored  in  a  cool,  dry  place.  While  the  treatment  of 
the  latex  of  Manihot,  on  account  of  its  greater  con- 
sistency, presents  greater  difficulty  than  that  of 
Hevea,  an  improvement  in  the  quality  of  the  rub- 
ber might  be  attained  by  more  suitable  manipula- 
tion. Instead  of  allowing  the  milky  juice  to  trickle 
down  the  trunk  of  the  tree,  it  might  be  caught  in 
cups  and  immediately  mixed  with  alkaline  water,  it 
mixing  in  a  fresh  state  better  with  this  than  with 


46  INDIA    RUBBER,  GUTTA    PERCHA,  BALATA. 

pure  water.  In  this  manner  the  latex  would  be 
kept  liquid  for  some  time  and  fumigation  might  be 
employed  for  its  coagulation.  In  Ceara,  experiments 
of  this  kind  have  been  made  with  excellent  results, 
but  unfortunately  the  natives  will  not  listen  to  any- 
thing new,  and  continue  their  old,  more  rapid  and 
less  laborious  method  of  preparation. 

The  Manihot  grows  upon  the  steep  granite  rocks 
of  Brazil  and  yields  only  small  quantities  of  very 
thick  milky  juice,  but  the  tree  flourishes  also  in 
the  plains  and  in  moist  soil,  in  which  case  the  latex 
is  thinner  and  more  abundant  and  could  be  readily 
subjected  to  the  above-mentioned  treatment. 

Coagulation  by  skimming  after  the  addition,  of  the 
same  quantity  of  water,  and  a  shorter  or  longer  rest. 
This  mode  of  separation  is  employed  in  Bahia  with 
the  latex  of  Han  am  tia,  in  some  regions  of  Nicaragua 
and  Central  America  with  the  latex  of  (1<i*1}I/<Hi,  mid 
in  Assam  with  the  latex  of  Ficns. 

In  Bahia  separation  is  effected  by  diluting  the 
latex  with  water  and  allowing  it  to  stand  quietly  for 
some  time.  Two  layers,  one  above  the  other,  are 
quickly  formed,  the  upper  one  being  butyraceous. 
When  this  has  acquired  sufficient  consistency,  it  is 
skimmed  off,  dried,  and  thus  brought  into  com- 
merce. 

In  Assam  the  rubber  prepared  in  this  manner  is 
placed  in  pots  over  a  fire,  whereby  drying  is  accel- 
erated. In  Central  America,  the  pieces  of  rubber 
are  first  rolled  with  wooden  rolls  to  remove  the 
excess  of  \vater  and  close  the  pores,  and  they  are 


RAW    MATERIAL.  47 

then  for  fourteen  days  exposed  to  the  sun  to  com- 
pletely dry  them,  when  they  are  rolled  together  and 
packed.  These  three  modes  of  preparation  are  very 
primitive  and  of  course  the  product  can  only  be 
rubber  of  an  inferior  quality.  The  loss  frequently 
amounts  to  50  per  cent.,  especially  when  the  rubber 
is  still  fresh.  It  will  be  readily  understood  that  this 
rubber  is  not  in  demand,  though  as  regards  elasticity 
and  power  of  resistance,  it  is  not  inferior  to  other 
varieties. 

Coagulation  by  rest  after  the  addition  of  four  to  Jive 
times  the  quantity  of  water.  This  method  is  employed 
011  the  Congo  for  treating  the  latex  of  Landolphia, 
and  has  been  described  in  detail  by  R.  P.  Merlon. 
With  a  sharp  instrument  incisions  are  made  which 
penetrate  the  bark  but  do  not  touch  the  heart  of  the 
plant,  as  otherwise  another  kind  of  milky  juice  ex- 
udes which  is  acrid,  very  watery  and  spoils  quickly. 
The  incisions  are  made  one  above  the  other  either 
in  a  straight  or  oblique  line.  Underneath  the  low- 
est incision  is  secured  by  means  of  rubber  or  clay  a 
broad  bent  leaf,  which  catches  the  latex  and  conducts 
it  to  a  bottle-gourd  on  the  foot  of  the  tree.  The 
lower  end  of  the  bottle-gourd  is  provided  with  an 
opening  which  however  is  temporarily  closed  with  a 
cork.  The  sap  exuding  from  the  plant  is  quite 
liquid  and  has  the  appearance  of  cow-milk  thick- 
ened by  long  boiling.  While  in  a  fresh  state  it  is 
mixed  with  four  to  five  times  its  quantity  of  water, 
which  accelerates  coagulation,  the  rubber  in  the  form 
of  cream  depositing  on  the  surface.  After  twenty -four 


48  INDIA    RUBBER,  GUTTA    PERCJIA,  BALATA. 

hours  the  cork  is  removed  from  the  opening  in  the 
lower  end  of  the  bottle-gourd,  and  the  water  together 
with  the  greater  portion  of  the  substances  producing 
putrefaction  runs  off,  while  the  rubber  remains  be- 
hind as  a  semi-fluid  mass.  For  complete  coagula- 
tion it  is  then  poured  into  wooden  vessels  and  for  a 
few  hours  exposed  to  the  air,  whereby  it  acquires 
greater  consistency  but  is  not  sufficiently  solid.  The 
mass  is  now  kneaded.  But  as  the  lower  portion  has 
become  too  hard  in  the  wooden  vessel  to  be  sub- 
jected to  this  manipulation,  it  is  cut  into  small  pieces 
or  discs  which  in  commerce  are  known'  as  "  thim- 
bles." 

The  rubber  thus  prepared  has  the  defect  of  con- 
taining quite  a  quantity  of  water  and  even  unde- 
composed  latex,  and  consequently  substances  pro- 
ducing fermentation,  which  soon  impart  to  it  a 
characteristically  disagreeable  odor.  To  overcome 
this  evil  the  product  is  washed,  which  however  is 
done  in  a  very  unsatisfactory  manner.  The  rubber 
is  spongy  and  full  of  holes  which  contain  a  whitish 
liquid  producing  the  above-mentioned  disagreeable 
odor.  The  loss  in  working  it  is  frequently  from  30 
to  40  per  cent. 

From  the  latex  of  Landolphia  other  varieties  of 
rubber  are  prepared  which  do  not  show  the  above- 
mentioned  defects,  and  this  proves  that  the  small 
value  of  this  product  is  due  to  irrational  treatment. 

Chemical  disintegration  by  mineral  reagents.  This 
process  being  quick  and  not  laborious,  it  is  no  won- 
der that  its  employment  has  rapidly  extended 


RAW    MATERIAL.  49 

throughout  Africa  as  well  as  America,  Pernambuco, 
and  Maranham  rubber  is  now  prepared  in  this  man- 
ner, as  well  as  several  varieties  on  the  Ivory  Coast. 

1.  Coagulation  by  alum.  This  process  is  employed 
in  Pernambuco  for  treating  the  milky  juice  of  Han- 
cftrnia,  and  is  known  as  the  Strauss  process  after  its 
inventor,  Heinrich  Anton  Strauss.  A  solution  of 
potash-alum  is  added  to  the  latex  and  coagulation 
takes  place  almost  immediately.  The  mass  is  then 
placed  for  eight  days  upon  hurdles  to  drain,  when 
it  is  cut  up,  dried  for  a  month  in  the  sun  and  thus 
brought  into  commerce. 

Strauss'  process,  according  to  Morellet,  is  very 
ingenious,  but  the  results  obtained  are  bad  and  do 
not  justify  the  enthusiasm  with  which  J.  Collins 
speaks  of  it.  He  says :  "  This  process,  which  has 
been  purchased  by  the  Pernambuco  government,  is 
an  excellent  one,  and  the  more  so  as  it  is  not  neces- 
sary to  employ  it  where  the  latex  is  gathered  and 
coagulation  takes  place  in  the  cold  way." 

The  rubber  prepared  in  this  manner  in  time  un- 
dergoes alteration,  and  when  it  becomes  older,  is 
changed  into  a  mass  of  little  market  value.  Al- 
though a  piece  of  such  rubber  when  fresh  is  quite 
elastic,  it  soon  loses  its  elasticity,  becomes  stiff  like 
pasteboard,  and  cannot  bear  mechanical  manipula- 
tion. It  becomes  granular  and  brittle,  and  alum 
effloresces  and  crystallizes  on  the  surface.  When 
such  rubber,  which  is  of  a  rose-color  inside  and  out, 
is  cut  up,  quite  a  number  of  holes  are  found  which 
contain  not  only  serum,  but  also  alum  water  used 
4 


50     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

for  coagulation.  By  pressing,  a  portion  of  this  alum 
water  might  be  removed  ;  but  independent  of  the 
fact  that  the  rubber-gatherer  has  not  always  a  press 
at  his  disposal,  evaporation  would  still  be  very  in- 
complete and  the  injurious  effect  of  the  alum  is  not 
overcome.  To  be  sure  this  mode  of  preparation  is 
economical  as  regards  labor,  but  the  product  suffers, 
and  the  loss  in  working  it  amounts  frequently  to  as 
much  as  60  per  cent. 

2.  Coagulation  by  sulphuric  acid  and  sea  salt.     In 
the  provinces  of  Maranham  and  Malto  G rosso,  sul- 
phuric  acid   diluted  with  water  is  substituted   for 
alum.     Like  all  other  acids,  sulphuric  acid  has  the 
property  of  effecting  coagulation,  which,  however, 
takes  place  so  rapidly  that  there  is  not  a  sufficient 
evaporation  of  the  water.     In  addition  to  this,  acids 
have  not  an  antiseptic  effect  and  the  product  shows 
the  same  defects  already  mentioned. 

Coagulation  may  further  be  effected  by  a  solution 
of  sea  salt,  and  as  its  antiseptic  action  is  well  known 
it  has  generally  replaced  sulphuric  acid  in  the  two 
provinces  mentioned  above.  Where  sea  salt  cannot 
be  obtained,  the  use  of  common  salt  might  be  recom- 
mended, which,  however,  leaves  a  larger  quantity 
of  water  in  the  rubber.  Some  African  varieties  of 
rubber  from  the  Ivory  Coast,  Cameroon  and  the 
Congo  resemble  these  American  varieties,  and  like 
them  their  preservation  is  chiefly  due  to  the  treat- 
ment with  salt  water. 

3.  Coagulation  by  soap  water.     This  peculiar  and 
remarkable  method  is  occasionally  employed  in  Peru 


RAW    MATERI 


in  the  treatment  of  the  latex  of  Hancornia.  E.  Bard 
describes  the  process  as  follows:  "  To  coagulate  the 
milky  juice  it  is  poured  into  large  wooden  vats  or 
pits  in  the  ground  having  a  capacity  of  about  65 
pounds  of  fluid.  The  soap  has  been  previously  dis- 
solved in  water,  about  four  ounces  of  it  being  used 
for  a  bucketful  of  water,  and  two  bucketfuls  of  this 
solution  are  considered  sufficient  for  65  pounds  of 
latex.  The  soap  solution  having  been  poured  into 
the  latex,  the  mass  is  beaten  with  the  hand,  which 
accelerates  coagulation.  The  rubber  is  formed  in 
the  shape  of  a  block.  To  drain  off  the  water  the 
rubber  is  punctured  in  various  places  with  a  knife." 

This  rubber  is  of  course  very  porous  and  contains 
a  considerable  quantity  of  water,  and  in  consequence 
of  the  primitive  treatment  quite  a  number  of  foreign 
substances  get  into  the  mixture.  It  is  difficult  to 
understand  the  effect  of  the  soap,  and  it  may  be  sup- 
posed that  the  coagulation  of  the  latex  is  promoted 
simply  by  the  addition  of  water,  which  renders  the 
latex  more  fluid  and  facilitates  the  separation  of  the 
globules  of  rubber  from  the  serum. 

It  remains  to  mention  here  the  experiments  re- 
garding the  various  methods  of  treating  the  latex  of 
Hevea  made  by  Dr.  Morisse,  a  member  of  Count 
Bertier's  expedition  in  1888  to  1889  to  the  Upper 
Orinoco.  Rousseau  in  his  excellent  article  on  rub- 
ber and  gutta-percha  gives  a  summary  of  these  ex- 
periments as  'follows: 

In  his  experiments  to  find  an  easy  method  for  the 
coagulation  of  the  latex  without  injury  to  the  qual- 


52  INDIA    RUBBER,  GUTTA    PRRCHA,  BALATA. 

ity  of  the  rubber,  Dr.  Morisse  employed  various 
agents  with  the  following  results  : 

One  part  of  90  per  cent,  alcohol  coagulates  six 
parts  of  rubber,  the  product  being  rubber  of  an  ex- 
cellent fine  quality  of  a  snow-white  color  which  does 
not  become  yellow  by  age.  On  account  of  its  cost- 
liness this  method,  of  course,  cannot  be  used  for  prac- 
tical purposes. 

Chloride  of  iron  disintegrates  the  latex  in  the  pro- 
portion of  1  :  9.  The  rubber  thus  obtained  forms  a 
coarse-grained  dust,  has  a  dirty  color  and  but  little 
coherence. 

One  part  of  alcoholic  solution  of  corrosive  subli- 
mate disintegrates  11  parts  of  milky  juice  and  yields 
a  good  quality  of  rubber. 

One  part  of  calcium  chloride  disintegrates  15  parts 
of  latex,  but  it  is  difficult  to  keep  this  deliquescent 
salt  in  a  climate  where  the  air  is  always  filled  with 
moisture. 

Chromic  acid  disintegrates  the  latex  in  the  pro- 
portion of  1 :  5,  while  the  action  of  nitric  acid  is  still 
less  effective. 

Non-crystallized  phenolsulphonic  acid  disinte- 
grates the  latex  in  the  proportion  of  1  :18.  The 
most  effective  agent,  however,  is  sulphuric  acid. 
Diluted  with  water  in  the  proportion  of  1  : 50,  it 
suffices  for  the  coagulation  of  10  quarts  of  milky 
juice.  It  is  even  effective  when  diluted  in  the  pro- 
portion of  1  : 100,  but  coagulation  takes  place  only 
by  agitating  the  mass,  and  besides  requires  consid- 
erable time, 


RAW   MATERIAL.  53 

Tincture  of  iodine  appears  to  be  effective  only  by 
reason  of  the  alcohol  it  contains.  Other  prepara- 
tions used  in  the  experiments  gave  no  remarkable 
results.  There  need  be  mentioned  here  only:  potas- 
sium carbonate,  bicarbonate  of  potash,  carbonate  of 
soda,  common  salt,  potassium  bromide,  potassium 
iodide,  ammonia,  ether,  chloroform,  carbon  disul- 
phide,  glycerine,  arsenious  acid,  etc. 

Alum,  which  has  been  successfully  used  for  the 
latex  of  several  rubber  trees,  gave  only  negative  re- 
sults with  Hevea  latex. 

The  first  piece  of  rubber  prepared  with  the  assist- 
ance of  sulphuric  acid  soon  became  spoiled  by  insects 
and  cryptogamia,  which  rapidly  developed  inside 
and  out.  Dr.  Morisse  then  concluded  to  mix  the 
sulphuric  acid  with  a  powerful  antiseptic  agent  and 
attained  his  object  by  the  use  of  phenol-sulphonic 
acid.  The  last  traces  of  this  acid  disappeared  from 
the  surface  only  six  months  after  coagulation,  but 
by  that  time  the  rubber  was  so  thoroughly  dried  out 
as  to  leave  no  fear  of  injurious  organizations.  After 
numerous  experiments,  the  following  solutions  were 
found  to  be  most  effective  : 

f  Phenol,  2.25  drachms. 

Solution  A.  <  Alcohol,  sufficient  to  dissolve  above. 
I  Water,  2  ozs.  13  drachms. 

Solution  B.  (  SulPhu™  «cid>  1-12  Caching. 

I  Water,  11.28  drachms. 

Mix  the  two  solutions  before  use.  With  slight 
agitation,  the  above  quantity  effects  the  instantane- 
ous coagulation  of  one  quart  of  milky  juice. 


54     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

In  most  cases  a  solution  composed  of  1  : 60  of  the 
first  and  1  :  30  of  the  second  acid  will  be  sufficient, 
but  allowance  must  be  made  for  the  fact  that  coagu- 
lation is  affected  by  the  temperature,  the  hygrome- 
tric  condition  of  the  air,  time  of  day,  etc. 

For  the  coagulation  of  1000  quarts  of  milky  juice, 
two  quarts  of  sulphuric  acid  and  four  quarts  of 
phenol  are  required,  and  hence  the  expense  of  the 
operation  is  very  small. 

From  the  quantity  of  milky  juice  above  men- 
tioned, about  220  pounds  of  Para  rubber  are  ob- 
tained, which  is  dry,  hard,  resistant,  solid  and  of 
good  appearance,  which  proves  the  availability  of 
this  method. 

From  what  has  been  said  it  will  be  seen  that  the 
latex  of  Hevea  is  not  affected  by  some  reagents 
which  produce  coagulation  of  the  milky  juice  of 
other  plants.  Further,  that  the  experiments  to  find 
in  addition  to  the  old  method  of  fumigation,  new 
processes  of  preparation  are  not  promising,  and  the 
less  so  as  experience  has  shown  that  rubber  prepared 
by  the  addition  of  any  kind  of  solution  decreases 
in  value." 

Rousseau's  conclusions  will  no  doubt  be  accepted 
as  correct.  The  excellent  quality  of  Para  rubber  is 
due  to  the  care  exercised  in  its  preparation,  and  to 
abandon  the  method  would  unavoidably  cause  con- 
siderable loss.  Beside,  the  antiseptic  effect  of  phenol 
appears  very  doubtful.  Creosote  alone  can  effect 
complete  sterilization,  and  only  when  USCM!  after 
every  layer,  and  under  the  influence  of  moderate 
heat. 


RAW    MATERIAL.  55 

Chemical  disintegration  by  the  addition  of  vegetable 
(igcnts.  This  method  is  in  use  in  Madagascar,  Gam- 
bia, Peru,  Guatemala  and  Nicagarua.  In  some 
cases  a  vegetable  acid  is  added  and  in  others  an  in- 
fusion, the  chemical  composition  of  which  is  not  de- 
finitely known,  but  the  action  of  which  is  very  likely 
more  or  less  due  to  the  presence  of  a  vegetable  acid. 

With  the  above  mentioned  African  varieties  of 
rubber,  coagulation  would  seem  to  be  effected  by 
means  of  citric  acid.  Morellet  says  :  "  In  examin- 
ing Madagascar  rubber,  grains  were  frequently  found 
which  were  recognized  as  seeds  of  Aurantiacesz.  It 
was  at  first  difficult  to  understand  how  these  ^eeds 
got  into  the  rubber,  but  as  they  were  found  too  fre- 
quently to  allow  of  their  presence  being  ascribed  to 
accident,  the  conclusion  was  reached  that  the  juice 
of  Aurantiacese  which  contains  citric  acid  was  used 
for  coagulation.  This  conclusion  was  later  on  con- 
firmed by  persons  who  had  traveled  in  those  regions." 

Cousin  asserts  that  while  residing  in  Casamanza 
he  had  obtained  by  this  method  an  amber-colored 
rubber,  which  was  nearly  transparent,  of  remarkable 
elasticity  and  durability.  However  this  assertion  is 
open  to  doubt,  because  while  vegetable  acids  have 
the  same  defect  as  mineral  acids  of  producing  coagu- 
lation too  rapidly,  they  are  besides  a  natural  breed- 
ing place  of  all  kinds  of  microbes  which  produce 
putrefaction.  This  opinion  is  also  confirmed  by  the 
fact  that  the  use  of  citric  acid  for  coagulation  has 
been  almost  entirely  abandoned  in  Madagascar,  and 
sulphuric  acid  substituted  for  it.  In  Peru  the  co- 


56     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

agulation  of  Hancornia  latex  is  occasionally  effected 
by  means  of  a  vegetable  juice  obtained  from  a  climb- 
ing plant  called  by  the  natives  Sachacamote.  In 
Guatemala  and  Nicaragua  the  latex  of  Castilloa  is 
treated  in  a  similar  manner.  Coagulation  is  effected 
by  an  infusion  of  the  root  of  Ipomcea  bona  nox  which 
is  widely  distributed  throughout  Central  America. 
In  fact  the  milky  juice  is  disintegrated  by  an  or- 
ganic acid  not  definitely  determined,  but  later  a  resin 
is  found  in  the  rubber  which  not  only  decreases  the 
industrial  yield  but  is  difficult  to  remove  and  trou- 
blesome in  manufacturing.  On  the  other  hand  the 
same  latex  with  different  treatment  yields  a  very 
elastic,  strong  and  profitable  rubber. 

Coagulation  by  a  combination  of  natural  or  artificial 
heat  with  chemical  disintegration.  In  Gambia  (Casa- 
manza,  Ivory  Coast)  the  method  employed  with 
Valea  and  other  climbing  plants  is  as  follows  :  The 
rubber  gatherer  makes  a  slight  incision  in  the  plant 
and  then  bruises  the  bark  somewhat.  Every  bruise 
is  rubbed  with  salt  water  and  the  incisions,  which 
are  about  If  to  2 J  inches  long,  are  arranged  so  that 
there  is  an  interval  of  about  four  inches  between 
them.  The  latex  immediately  exudes  as  a  thick 
white  liquid.  Under  the  influence  of  the  salt  solu- 
tion the  separation  of  serum  and  rubber  takes  place 
immediately,  the  globules  of  rubber  running 
together  and  forming  small  lumps.  The  gatherer 
then  takes  a  little  rubber  from  each  incision  and 
combines  these  particles  to  a  ball  in  his  hand.  But 
as  the  mass  is  very  viscous,  each  portion  neverthe- 


RAW    MATERIAL.  57 

less  remains  connected  with  the  incision  from  which 
it  exudes,  so  that  a  thread  of  rubber  extends  from 
each  incision  to  the  hand  of  the  workman.  The 
latter  commences  now  to  roll  these  threads,  which 
are  constantly  formed  by  the  uninterrupted  exuda- 
tion of  latex,  into  a  ball.  In  consequence  of  the  ex- 
tension and  subsequent  pressing  between  the  fingers, 
the  interior  threads  stick  together  as  soon  as  they 
are  covered  by  fresh  threads,  and  the  formation  of 
th reads  is  visible  only  on  the  outside,  and  unwinding 
of  the  ball  is  impossible.  The  bruises  must  of 
course,  from  time  to  time,  be  moistened  with  salt 
water.  The  rubber  thus  obtained  is  at  first  nearly 
white,  but  becomes  darker  in  time  and  acquires  a 
reddish  color. 

The  weight  of  such  balls  varies  between  9  and  28 
ounces,  though  some  weighing  over  4J  pounds  are 
also  brought  into  commerce.  Since  the  workman 
cannot  hold  these  large  balls  between  his  fingers,  to 
roll  them  up,  he  lies  down  on  his  back,  places  the 
ball  upon  his  body,  holds  it  with  one  hand  and  con- 
tinues rolling  until  the  plant  is  exhausted  (Chapel). 

This  method,  by  which  natural  and  artificial  heat, 
together  with  a  powerful  antiseptic,  act  uninterrupt- 
edly upon  very  small  quantities  of  rubber,  can  be 
highly  recommended,  especially  where,  on  account 
of  local  conditions  or  the  constitution  of  the  latex, 
fumigation  is  not  possible.  Every  single  thread  is 
also  exposed  to  the  air  and  the  heat  of  the  hand  of 
the  workman,  which  promotes  the  evaporation  of 
the  serum.  To  be  sure  the  operation  is  rather  labor- 


58  INDIA    RUBBER,  GTJTTA    PERCHA,  BALATA. 

ious.  This  method  has  another  great  advantage, 
namely  that  the  product  obtained  is  perfectly  pure, 
it  containing  no  vegetable  or  mineral  admixture,  ex- 
cept such  as  the  workman  intentionally  adds.  How- 
ever, by  doing  so  he  hurts  himself  most,  because  if  the 
trader's  suspicion  is  once  aroused,  it  becomes  difficult 
and  frequently  even  impossible  to  sell  the  product. 

The  various  methods  of  coagulating  crude  rubber 
have  now  been  described,  and  the  result  of  experi- 
ence and  experiments  up  to  the  present  time  may  be 
summarized  as  follows : 

1.  In  choosing  the  method  of  coagulation  the  den- 
sity of  the  milky  juice  must  be  taken  into  consider- 
ation.     Vahea  and  Manihot  yield  thicker  latex,  and 
Hevea,  Castilloa,  Landolphia  and  Ficus,  a  more  fluid 
one.     Hence  it  would   be  incorrect  to  treat   both 
kinds  in  the  same  manner. 

2.  Care  must  be  had  to  produce  rubber  containing 
as  little  water  and  substances  producing  fermenta- 
tion as  possible.     Further,  efforts  should  be  made 
to  keep  the  rubber  free  from  foreign  substances,  in- 
troduced either  accidentally  or  intentionally,  as  such 
admixtures,  independent  of  decreasing  the  value  of 
the  product,  always  give  rise  to  suspicion  of  fraud. 
In  this  respect  two  methods  can  be  especially  re- 
commended, namely,  coagulation  by  fumigation  and 
coagulation  by  artificial  or  natural  heat  with  the 
addition  of  common  salt. 

3.  The  use  of  mineral  and  vegetable  acids,  as  well 
as  alum,  and  the  addition  of  water,  no  matter  in 
what  form,  always  injures  the  quality  of  the  pro- 
duct, and  should,  therefore,  be  avoided. 


RAW    MATERIAL.  59 

4.  The  shape  in  which  rubber  is  stored  is  of  im- 
portance.    It  has  been  observed  that  rubber  keeps 
less  well  the  larger  the  separate  pieces  are,  especially 
when  other  fluids  have  been  used  in  its  preparation. 
This  is  readily  explained,  because  the  greater  the 
surface  presented  the  more  moisture  will  evaporate, 
and  the  quality  of  the  product  is  improved  by  dry- 
ing out  and  the  formation  of  putrefaction  prevented. 

5.  The  mixing  of  different  kinds  of  milky  juice 
should  be  avoided,  since  the  inferior  latex  will  in- 
jure the  better  kind  so  that  the  product  becomes  of 
less  value  and  the  quality  is  more  or  less  altered. 

6.  A  knowledge  of  the  chemical  composition  of 
every  kind  of  latex  would  considerably  contribute 
towards  determining  the  exact  method  to  be  used  in 
every  case ;  but  unfortunately  sufficient  information 
in  this  respect  is  lacking,  and  it  would  be  of  great 
benefit  to  the  rubber  industry  if  chemists  and  nat- 
uralists would  devote  their  attention  to  this  subject. 
Adriani  has  endeavored  to  give  an  exact  analysis  of 
the  latex  of  the  Indian  Ficus,  and  below  the  com- 
position of  Hevea  latex  will  be  given  as  accurately 
as  possible,  but  regarding  the  composition  of  the 
milky  juice  of  other  rubber  plants  information  is 
wanting.     Such  information,  however,  would  be  of 
great  use  not  only  in  choosing  the  best  mode  of  coag- 
ulation, but  also  for  storing  the  different  varieties  of 
rubber. 

7.  A  better  knowledge  of  the  milk  vessels,  their 
arrangement  and   development  in  reference  to  the 
other  organs  of  the  bark,  would  also  be  desirable. 


60     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

But  little  attention  has  been  paid  to  this  subject,  and 
such  study  would  give  valuable  hints  regarding  the 
quality  *and  treatment  of  rubber.  Morellet  has 
microscopically  examined  the  bark  of  a  few  rubber 
plants  and  it  would  be  well  if  his  example  were  fol- 
lowed and  the  research  extended  to  all  rubber  plants. 

Chemical  and  Physical  Properties  of  Crude  Rubber. 

Crude  rubber  as  brought  into  commerce,  being 
the  inspissated  or  dried  sap  of  certain  varieties  of 
plants,  it  will  be  necessary  to  consider  first  the  fresh 
milky  juice  as  it  exudes  from  the  plant,  and  for  this 
purpose  that  of  Hevea  brasiliensis,  being  more  or  less 
typical,  may  be  selected.  It  is  a  fluid  which  to  the 
uaked  eye  appears  white,  but  in  reality  it  is  color- 
less, or  at  the  utmost  has  a  slight  amber-color  tinge. 
It  contains  a  quantity  of  globular  bodies  with  an 
average  diameter  of  3.5  micromillimeters.*  These 
globules  are  the  actual  rubber,  and  though  colorless 
themselves,  they  impart  by  their  diffusion  to  the 
entire  fluid  a  milk-white  appearance. 

The  fresh  latex  of  Hevea  is  odorless,  but  by  expo- 
sure to  the  air  it  acquires,  by  the  action  of  oxygen, 
an  odor  of  methylamine,t  which  is  found  in  all 
varieties  of  rubber  not  fumigated  for  the  purpose  of 
sterilization.  The  Para  varieties  of  second  quality, 
which  consist  of  a  mixture  of  fumigated  and  non- 

*  One  micromillimeter  is  the  thousandth  part  of  a  milli- 
meter. 

f  A  colorless  gas,  having  an  ammonincnl  and  slightly  fishy 
odor. 


RAW    MATERIAL.  61 

fumigated  rubber,  also  show  this  peculiar  odor. 
The  taste  of  fresh  Havea  milky  juice  is  not  pro- 
nounced, it  being  rather  agreeable  and  sweetish  than 
disagreeable  and  bitter.  Its  specific  gravity  is  diffi- 
cult to  determine,  it  being  affected  by  many  acci- 
dental influences,  but  as  a  rule  milky  juice  of  less 
specific  gravity  is  richer  in  elastic  mass.  The  spe- 
cific gravity  of  typical  latex  of  Hevea  brasiliensis,  at 
a  temperature  of  58°-F.  is  about  1.019,  with  a  con- 
tent of  about  32  per  cent,  of  rubber. 

The  chemical  composition  of  the  latex  of  Hevea 
hrasilienxis  as  it  exudes  from  the  tree  is  as  follows : 

Elastic  constituents .         .     32       per  cent. 

Organic,  nitrogenous  con- 
stituents      .         .         .       2.30    "       " 

Mineral  salts  .         .         .       9.70    "      " 

Resinous  constituents       .       traces. 

Slightly  alkaline  water  .  55-56  per  cent. 
The  chemical  and  physical  properties  of  crude 
rubber  also  show  considerable  variations  according 
to  its  origin,  mode  of  obtaining  it  and  subsequent 
treatment.  The  better  qualities  have  a  more  or  less 
characteristic  odor,  that  of  fumigated  varieties  being 
not  disagreeable  and  resembling  the  odor  of  smoked 
bacon.  On  the  other  hand,  non-fumigated  varieties 
and  those  of  inferior  quality  containing  water  have 
frequently  a  disagreeable,  and  in  many  cases  ah 
offensive  odor.  The  specific  gravity :is  0.92  to  0.96. 
Crude  rubber  consists  chiefly  of  a  mixture  of  hy- 
drocarbons, and  according  to  some  analyses  it  has 
the  formula  C4H7,or  C6H10,  or  C6H8.  However, 


62  INDIA    RUBBER,  GUTTA    PERCHA,  BALATA. 

according  to  the  most  recent  researches  it  is  composed 
of  C45H36.  While  this  may  be  of  little  interest  to 
the  practical  man,  some  varieties  of  rubber  contain 
certain  substances  which  deserve  attention. 

When  rubber  is  treated  with  alcohol  certain  com- 
binations are  dissolved  and  are  deposited  in  the 
form  of  crystals  after  the  evaporation  of  the  alcohol. 
The  crystals  dissolve  readily  in  water,  but  there  is 
considerable  variation  in  their  properties.  By  treat- 
ing these  combinations  with  solution  of  hydrogen 
iodide,  they  split  into  new  bodies  and  not  into  fer- 
mentable varieties  of  sugar.  The  bodies  soluble  in 
alcohol  have  been  called  dambonite,  bornesite  and 
matezite,  the  first  being  found  in  African  rubber,  the 
second  in  Borneo  rubber  and  the  last  in  Madagascar 
rubber.  Their  composition  is  as  follows  : 

Dambonite,  C4H8O3  Dambose,  C3H6O3 

Bornesite,     C7HUO6  Borneodambose,    C6H,.2O6 

Matezite,      C]0H20O9  Matezitedambose,  C9H18O9 

Although  rubber  is  distinguished  by  its  great 
chemical  indifference,  it  is  very  sensitive  to  certain 
influences,  especially  to  light,  and  oxygen  and  sul- 
phur have  great  effect  upon  it. 

That  a  change  in  the  substance  of  rubber  is  pro- 
duced by  light,  is  shown  by  the  following  experi- 
ment :  If  rubber  be  exposed  to  the  direct  rays  of  the 
sun  and  then  pressed  upon  a  lithographic  stone,  the 
portion  of  the  latter  brought  in  contact  with  it  will 
take  and  hold  printing  ink,  while  rubber  not  ex- 
posed to  the  sun  fails  to  produce  this  effect. 


KA\V    MATERIAL.  63 

If  rubber  be  stored  for  a  considerable  time — sev- 
eral years — where  it  is  exposed  to  the  air,  it  suffers 
considerable  change,  at  least  on  the  surface.  If 
such  rubber  be  treated  with  a  solvent,  for  instance 
benzene,  a  body  is  dissolved  in  the  latter  which  re- 
mains behind  after  the  evaporation  of  the  solvent 
and  shows  the  physical  properties  of  a  resin  very 
rich  in  oxygen  and  not  soluble  in  carbon  disulphide 
nor  in  oil  of  turpentine — both  solvents  of  rubber. 
This  proves  that  by  long-continued  exposure  to  the 
air,  partial  oxidation  of  the  rubber  has  taken  place. 

According  to  C.  A.  Burghardt,  rubber  gradually 
oxidizes,  while  a  resin  readily  soluble  in  alkalies  is 
formed  which  contains  27.3  per  cent,  of  oxygen  and 
besides  a  mass  insoluble  in  alkalies  and  benzene  is 
formed  which  contains  up  to  20  per  cent,  oxygen. 
Fresh  vulcanized  rubber  contains  three  per  cent,  of- 
the  first  resin,  but  none  of  the  latter. 

By  coaling  rubber  with  oil,  especially  olive  or 
palm  oil,  its  destruction  is  accelerated,  because  these 
bodies  promote  the  action  of  oxygen.  Rubber 
brought  in  contact  witli  copper  or  copper  combina- 
tions is  also  rapidly  ruined.  Rubber  to  which  in 
vulcanizing  an  excess — more  than  2  to  2J  per  cent. 
— of  sulphur  has  been  added  is  quickly  destroyed 
by  the  sulphuric  acid  formed  from  the  sulphur. 

The  content  of  water  in  good  rubber  amounts  to 
only  0.5  per  cent.,  while  old  rubber  articles  which 
have  become  hard  contain  5  to  10  per  cent.,  which 
escapes  completely  only  at  248°  F. 

When  rubber  becomes  hard  and  brittle,  a  chemi- 


64  INDIA    RUBBER,  GUTTA    PERCHA,  BALATA. 

cal  change  evidently  takes  place,  the  content  of 
carbon  decreasing,  as  shown  by  the  following  an- 
alyses by  Burghardt : 


I. 

II. 

III. 

IV. 

V. 

Carbon  .... 

77.91 

72.53 

70.43 

65.09 

64.00 

Hydrogen  .  .  . 
Sulphur  ... 
Oxygen  .... 

10.33 
5.15 
6.61 

11.31 
1.97 
14.19 

10.59 
3.14 
15.84 

10.00 
1.95 

22.96 

9.26 
2.28 
24.46 

No.  I  was  good  material,  but  contained  too  much 
sulphur ;  Nos.  II,  III  and  IV  were  more  or  less 
brittle,  and  No.  V  very  hard  and  brittle. 

Neither  cold  nor  warm  water  dissolves  rubber, 
but  boiling  water  extracts  from  some  varieties  a 
resin-like  substance.  In  warm  water  it  becomes 
very  soft  and  swells  up  considerably,  dark  pieces 
becoming  lighter  and  the  whole  mass  more  suscept- 
ible to  solvents;  but  on  being  exposed  to  the  air  for 
some  time,  the  normal  condition  is  restored.  The 
pale  color  of  light,  opaque  varieties  of  rubber  is  due 
to4a  content  of  water ;  after  drying,  the}  are  trans- 
parent and  dark. 

Rubber  is  capable  of  absorbing  as  much  as  18  per 
cent,  of  its  weight  of  water,  its  volume  at  the  same 
time  increasing  to  as  much  as  10  per  cent. 

Behavior  towards  sulphur.  The  behavior  of  rub- 
ber towards  sulphur  is  of  great  interest  to  the  man- 
ufacturer. Brought  in  contact  with  melted  sulphur, 
it  absorbs  it  very  freely  and,  according  to  the  quan- 
tity of  sulphur  used  and  the  temperature  to  which 
the  mixture  is  heated,  two  substances  are  produced 
showing  very  different  properties, 


RAW    MATERIAL.  65 

If  rubber  is  treated  with  a  small  quantity  of  sul- 
phur and  the  mixture  heated  for  a  short  time,  a 
gray  substance  is  obtained  possessing  great  elasticity, 
which  does  hot  vary  much  even  under  changes  of 
temperature.  The  product  thus  formed  is  known 
as  vulcanized  rubber  or  'vulcanite. 

But  if  rubber  is  treated  with  a  large  quantity  of 
sulphur  at  a  high  temperature  for  a  considerable 
time,  it  gradually  acquires  properties  entirely  differ- 
ent from  its  original  ones.  It  is  black,  possesses  but 
little  elasticity,  and  as  regards  its  physical  proper- 
ties, may  be  best  compared  with  horn.  This  sub- 
stance is  known  as  hard  rubber  or  ebonite. 

Behavior  towards  solvents.  Solutions  of  rubber  are 
of  great  importance  for  many  industrial  purposes, 
the  manufacture  of  water-proof  tissues,  of  rubber 
lacquers  and  varnishes,  etc.,  depending  on  them. 
The  behavior  of  rubber  towards  solvents  is  different 
from  that  of  most  substances,  which  are  either  solu- 
ble or  insoluble,  and  in  this  respect  it  very  much  re- 
sembles resins.  Although  not  soluble  by  certain 
agents,  it  will  swell  up  when  brought  in  contact 
with  them,  and  thereby  acquire  the  property  of 
being  soluble  in  many  substances  to  which  other- 
wise it  is  entirely  indifferent. 

In  many  solvents,  for  instance,  in  a  mixture  of 
alcohol  and  carbon  di sulphide,  rubber  swells  up  to 
thirty  times  its  original  volume,  and  in  preparing 
solutions  of  it,  this  must  be  taken  into  considera- 
tion. 

Among  the  substances  capable  of  dissolving  rub- 
5 


66     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

ber  in  the  actual  sense  of  the  word  may  be  men- 
tioned :  Ether,  benzene,  oil  of  turpentine,  essential 
oils,  and  tar  oils  in  general,  as  well  as  caoutchoucine, 
an  oily  product  obtained  by  the  destructive  distilla- 
tion of  rubber.  Fat  oils  heated  to  a  high  tempera- 
ture will  also  dissolve  it,  but  it  is  questionable 
whether  the  resulting  products  can  be  actually  con- 
sidered as  solutions  of  unaltered  rubber. 

However,  the  substances  named  above  are  not 
capable  of  holding  the  entire  mass  in  solution,  and 
can  absorb  only  a  certain  proportion  of  it.  To  ob- 
tain the  best  solutions,  the  rubber,  as  well  as  the 
solvent,  should  be  as  free  from  water  as  possible,  and 
two  solvents  should  be  used,  allowing  the  rubber  to 
swell  up  in  one  and  then  dissolving  it  in  the  other. 
Some  experiments  have  been  made  as  to  the  solu- 
bility of  different  varieties  of  rubber,  the  solvents 
used  being  entirely  free  from  water  and  the  rubber 
having  been  previously  dried  for  one  week  over 
sulphuric  acid.  These  experiments,  as  shown  by 
the  results  given  below,  prove  that  different  vari- 
eties are  soluble  in  various  proportions. 

Of  1 00  parts  of  dried  rubber  were  dissolved  : 
In  carbon  disulphide       .     65  to  70  parts. 
In  benzene      .         .         .     48  to  52      " 
In  oil  of  turpentine .         .     50  to  52      " 
In  caoutchoucine    .         .     53  to  55      " 
In  ether .         .         .         .     60  to  68      " 
If  the  solutions  are  allowed  to  evaporate,  a  color- 
less mass  of  considerable  elasticity  is  left  behind, 
which,  however,  does  not  possess  all  the  properties 


RAW    MATERIAL.  67 

of  rubber,  its  behavior  differing  from   the  latter, 
especially  when  subjected  to  heat. 
According  to  T.  F.  Hanausek  : 

Ceara  Nigger-  Sierra 

rubber,  head.  Leone. 

Parts.  Parts.  Parts. 

100  parts  of  ether    ......  dissolve    2.6  3.6  4.5 

"     oil  of  turpentine  .        "          4.5  5.0  4.6 

"            "     chloroform    ...                    3.0  3.7  3.0 

"     benzene  .   .    .  •    .                    1.5  4.5  4.0 
"     carbon  disulphide       "          0.4 

The  portion  of  the  rubber  which  remained  behind 
after  repeated  treatment  with  the  above-mentioned 
solvents,  showed  a  brown  color  similar  to  that  of  the 
product  originally  used,  possessed  little  elasticity 
but  considerable  tenacity.  When  examined  with  a 
microscope,  immediately  after  treatment  with  the 
solvent,  it  appears  like  a  wide-meshed  net,  but  in 
drying  it  contracts  considerably. 

As  has  previously  been  mentioned,  to  effect  a 
complete  solution  of  rubber  requires  certain  manip- 
ulation, and  may  be  best  done  as  follows :  Allow 
the  rubber  to  swell  up  in  carbon  disulphide,  which 
is  most  rapidly  effected  in  a  closed  tank  in  a  moder- 
ately warm  place.  Then  add  10  parts  of  absolute 
alcohol  for  every  100  parts  of  carbon  disulphide 
used.  Solution  will  be  complete  in  a  few  days,  and 
by  allowing  the  mass  to  stand  quietly  for  a  sufficient 
length  of  time,  all  foreign  admixtures  will  settle  on 
the  bottom. 

By  mixing  the  solution  with  a  large  quantity  of 
alcohol,  the  rubber  is  again  precipitated  in  a  spongy 


68     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

form,  while  the  foreign  substances  remain  in  solu- 
tion. By  pouring  off  the  brownish  solution  from 
the  precipitate  and  repeating  the  same  operation 
several  times,  the  rubber  is  obtained  free  from  col- 
oring matter,  as  an  entirely  white  mass,  or  showing 
at  the  utmost  only  a  slightly  yellowish  color. 

The  use  of  carbon  disulphide  as  a  solvent  is,  how- 
ever, objectionable,  on  account  of  its  great  volatility 
and  also  its  poisonous  fumes,  and  oil  of  turpentine 
is,  therefore,  recommended  as  a  substitute  for  the 
preparation  of  rubber  solutions.  But  the  ordinary 
commercial  oil  of  turpentine  always  contains  a.  con- 
siderable percentage  of  water,  and  does  not  effect 
complete  solution.  Hence,  for  the  preparation  of 
large  quantities  of  solution,  it  is  advisable  to  free 
the  oil  of  turpentine  from  water,  which  may  be 
effected  in  various  ways.  The  simplest  plan  is  to 
pour  it,  together  with  about  10  per  cent,  of  its  weight 
of  sulphuric  acid,  into  a  tank,  cover  the  latter  tightly, 
and  let  it  stand  quietly  until  the  solve.it  is  to  be 
used.  The  sulphuric  acid  forms  a  sediment  on  the 
bottom  of  the  tank,  from  which  the  oil  of  turpentine 
can  be  readily  drawn  off.  In  place  of  sulphuric 
acid,  fused  calcium  chloride  can  be  used  with  equal 
success. 

For  the  treatment  of  larger  quantities  of  oil  of 
turpentine,  it  is  advisable  to  rectify  it  over  quick- 
lime and  to  pass  the  vapor,  before  it  condenses, 
through  a  nearly  red-hot  pipe.  By  this  process,  the 
character  of  the  oil  of  turpentine  is  much  improved, 
and  it  is  much  better  adapted  as  a  solvent. 


RAW    MATERIAL.  69 

The  solution  of  rubber  is  readily  effected  by  cut- 
ting it  into  small  pieces  and  placing  them  in  linseed 
oil  heated  to  a  point,  when  it  throws  out  heavy 
vapors  and  is  in  a  state  of  ebullition.  But  it  is 
scarcely  possible  that  in  a  solution  thus  prepared 
there  is  any  unaltered  rubber,  and  it  is  very  likely 
that  it  only  contains  products  of  decomposition  of 
it.  For  certain  purposes  such  solution  is,  however, 
very  useful.  When  applied  in  a  thin  layer  to  an 
article  and  exposed  to  the  air,  it  dries  to  a  transpar- 
ent layer  distinguished  by  great  tenacity. 

Caoutchoucine,  or  oil  of  caoutchouc,  which,  as 
previously  mentioned,  is  obtained  by  destructive 
distillation  of  rubber,  has  been  recommended  as  a 
solvent  without,  however,  being  especially  suitable 
for  the  purpose.  Its  power  of  dissolving  rubber  is 
only  slightly  greater  than  that  of  anhydrous  oil  of 
turpentine,  and  the  cost  of  producing  it  is  compara- 
tively great. 

It  would  seem  that  for  practical  purposes  the 
most  suitable  solvents  are  carbon  disulphide  in  com- 
bination with  absolute  alcohol,  and  anhydrous  oil 
of  turpentine.  To  be  sure,  benzene  and  coal-tar  oil 
are  also  good  solvents,  but  they  have  the  disadvan- 
tage that  their  disagreeable  odor  adheres  for  a  long 
time  and  very  tenaciously  to  the  rubber.  Lascelles 
recommends  92  per  cent,  benzene  and  4  to  8  per 
cent,  of  eucalyptus  oil  as  a  solvent. 

In  case  solution  is  to  be  effected  by  means  of 
carbon  disulphide  and  absolute  alcohol,  it  is  advis- 
able for  the  manufacturer  to  prepare  the  latter  him- 


70  INDIA    RUBBER,  GUTTA    PERCHA,  BALATA. 

self,  which  may  be  done  as  follows  :  Bring  95  to  96 
per  cent,  alcohol  into  a  flask  previously  filled  about 
one-fifth  full  with  blue  vitriol  which  has  been 
heated  to  such  a  degree  that  the  blue  color  has 
been  changed  to  white.  The  vitriol  absorbs  all 
traces  of  water  from  the  alcohol  whereby  it  grad- 
ually reassumes  its  original  blue  color,  while  the 
supernatant  alcohol  has  become  entirely  anhydrous, 
i.  e.,  absolute  alcohol. 

According  to  C.  Fry's  patented  method  solutions 
of  rubber  and  gutta-percha  can,  it  is  claimed,  be 
prepared  with  great  facility  if  the  solvent — coal-tar 
oil  or  oil  of  turpentine — is  distilled  with  a  small 
quantity  of  rubber  or  gutta-percha.  The  crude  oil 
is  brought  into  a  still,  and  to  each  11  Ibs.  of  it  are 
added  6J  to  9  ozs.  of  rubber  or  gutta  percha. 

The  solvent  is  distilled  off,  and  the  residue  re- 
maining in  the  still  used  for  producing  coarser 
tissues.  It  is  claimed  that  solvents  prepared  in 
this  manner  are  best  adapted  for  the  oolution  of 
rubber  and  gutta  percha.  If  such  be  actually  the 
case  their  superiority  is  very  likely  due  to  an 
admixture  of  decomposed  products  of  rubber,  many 
of  them  being  excellent  solvents  of  the  latter.  It 
has  also  been  suggested  to  distil  rectified  spirits 
with  rubber  in  the  same  manner  as  described,  the 
dissolving  power,  it  is  claimed,  being  thereby  con- 
siderably increased.  However,  since  petroleum  lias 
come  into  use  for  preparing  rubber  solutions,  which 
will  be  referred  to  later  on,  and  as  carbon  disul- 
phide  and  the  light  tar  oils  can  be  procured  at  very 


RAW    MATERIAL.  71 

low  prices,  the  question  as  to  solvents  for  rubber 
has  lost  much  of  the  importance  it  formerly  pos- 
sessed, and  at  the  present  time  rubber  solutions  of 
any  desired  consistency  are  readily  prepared. 

Behavior  in  heat.  At  50°  F.  rubber  is  compara- 
tively solid,  and  not  very  elastic,  at  96.8°  F.  it  is 
soft  and  elastic  to  a  high  degree ;  gradual  increase 
of  heat  decreases  the  elasticity,  and  at  248°  F. 
it  liquefies  and  emits  a  peculiar  odor.  When  it 
has  been  heated  to  the  melting  point  it  congeals 
on  cooling  to  a  mass,  which  remains  sticky  for  a 
long  time.  If  exposed  to  a  still  greater  heat,  it 
ignites  and  is  consumed  with  a  bright  and  sooty 
flame. 

But  if  treated  at  a  high  temperature  in  a  closed 
vessel,  that  is,  if  it  is  subjected  to  destructive  distil- 
lation, there  is  obtained,  besides  the  coal  which  is 
deposited,  a  quantity  of  gas,  and  a  fluid  called  oil 
of  caoutchouc,  which,  as  has  been  stated,  is  a  sol- 
vent for  rubber. 

The  crude  oil  of  caoutchouc  (caoutchoucine) 
gained  by  destructive  distillation,  is  a  mixture  of 
several  combinations  of  hydrocarbons,  some  of 
which  are  characteristic  of  rubber,  while  others 
appear  also  in  the  destructive  distillation  of  other 
organic  substances. 

By  heating  rubber  in  vacuum  to  a  temperature 
above  392°  F.  a  mixture  of  isoprene,  caoutchene 
and  heveene  is  formed.  Gladstone  and  Hilbert 
have  adopted  for  these  combinations  the  following 
compositions  : 


72     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

Rubber  ....     UC6C4H16 

Isoprene         ....     C4CH8 
Caoutchene    ....     C4C6H16 
Heveene         .         .         .         .     nC2C8H8 

The  following  bodies  have  thus  far  been  determined 
as  being  present  in  oil  of  caoutchouc:  Eupione,  buty- 
lene,  caoutchin,  caoutchene  or  dipentene,  isoprcne 
and  heveene.  Caoutchin  forms  at  — 0.4°  F.  a  white 
crystalline  mass  consisting  of  needles  which  at  14° 
F.  fuses  to  a  transparent  oil  and  boils  at  58.5°  F. 
Isoprene  is  a  water-clear,  very  mobile  liquid  which 
boils  between  98.5°  and  100.5°  F.  By  the  admis- 
sion of  air  it  loses  its  fluidity,  becomes  sticky  and 
absorbs  ozonized  oxygen  with  avidity.  Eupione, 
butylene  and  isoprene  are  chiefly  found  in  the  por- 
tion of  the  distillate  which  passes  over  first,  and 
must  be  collected  in  vessels  thoroughly  cooled  off. 

The  greater  portion  of  caoutchene  is  found  in  the 
part  of  the  distillate  which  passes  over  between 
284°  and  530°  F.  When  pure  it  boils  at  330.8°  F., 
and,  what  is  very  remarkable,  congeals  only  at  a 
temperature  below  — 40°  F.  It  also  absorbs  oxy- 
gen with  avidity. 

Heveene,  which  is  contained  in  the  last  portions 
of  the  distillate  passing  over,  is  an  amber-colored 
oil,  of  specific  gravity  0.92  at  70°  F.  It  boils  at 
599°  F.,  does  not  congeal  in  the  cold,  has  a  slightly 
empyreumatic  odor,  an  acrid  taste,  and  consists  of 
86.11  percent,  carbon  and  14.02  percent,  hydrogen. 

According  to  Bouchardat,  11  Ibs.  of  fresh  Para 
rubber  yield  8.81  ozs.  isoprene,  70J  ozs.  caoutchene 


RAW    MATERIAL.  73 

(dipentene),  and  21.16  ozs.  heveene.  There  are 
formed  besides,  polyterpenes  boiling  at  a  higher 
temperature  than  heveene  and  only  a  small  quantity 
of  gases,  carbonic  oxide,  methane  and  ethylene. 

Among  the  products  of  distillation,  caoutchene 
and  eupione  are  the  most  effective  solvents.  In  the 
former  rubber  swells  up  very  much  and  a  consider- 
able quantity  of  it  is  dissolved  by  boiling,  the  solu- 
bility increasing  in  proportion  to  the  percentage  of 
eupione  contained  in  the  solvent. 

If  oil  of  caoutchouc  is  to  be  prepared  for  use  as  a 
solvent,  the  receiver  in  which  the  products  of  distil- 
lation are  collected  must  be  thoroughly  cooled  so  as 
to  retain  the  very  volatile  eupione  in  the  distillate, 
and,  of  course,  the  bottles  in  which  the  oil  of  caout- 
chouc is  kept  must  be  hermetically  closed. 

Commercial  Rubber. 

The  varieties  of  crude  rubber  occurring  in  com- 
merce may,  according  to  their  origin,  be  arranged 
in  three  principal  classes  as  follows : 

T     4         •  i  i       f  South  American  rubber. 

I.  American  rubber^ 

I  Central  American  rubber. 

II.  African  rubber     /  East  African  mbber 
I  West  African  rubber. 

III.  Asiatic  rubber. 

IV.  Australian  rubber. 

In  commerce  these  varieties  are  not  always  known 
by  regular  names,  the  separate  kinds  being  some- 
times called  after  the  province  of  their  origin,  though 
sometimes  other  regions  yield  the  same  kind  of  pro- 


74     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

ducts,  and  sometimes  after  the  shipping  place  or  the 
city  which  is  the  center  of  trade  for  the  respective 
variety.  A  brief  summary  of  the  best  known  vari- 
eties, including  their  commercial  names,  place  of 
origin,  form  in  which  they  are  brought  into  com- 
merce, appearance,  properties,  etc.,  is  given  below  : 

I.  AMERICAN  RUBBER.  1.  SOUTH  AMERICA  : 
Fine  Para;  Seringa  fina,  called  by  the  natives  Bor- 
racha  or  Jebe.  Origin :  Amazon  river,  Brazil. 
Form :  Biscuits  or  loaves  ;  weight  of  the  pieces  from 
the  Lower  Amazon,  6|  to  11  Ibs.;  from  the  Upper 
Amazon,  22  to  33  Ibs.  Appearance :  Dark  brown  to 
blackish.  Cut  surface  :  Darker  towards  the  outside, 
whitish  towards  the  inside.  The  separate  layers 
can  be  recognized  as  leaves  or  skins.  Odor :  Like 
smoked  bacon.  Adulteration :  Few  foreign  sub- 
stances ;  sometimes  mixed  with  the  latex  of  Minu- 
sops  elata,  Marcandaruba.  Moisture  varies  according 
to  the  time  of  gathering.  Loss  in  ivorking :  10  to  15 
per  cent.  Strong  and  elastic.  The  biscuits  fre- 
quently bear  the  name  of  the  factory. 

Entrefine  Para  ;  \  fine  Entrefine  ;  Grossa,  Origin  : 
Amazon  river.  Form :  Biscuits  or  loaves,  those 
from  the  Lower  Amazon  weighing  from  6J  to  11 
Ibs.  each,  and  those  from  the  Upper  Amazon  22  to 
33  Ibs.  each.  Appearance :  Dark  brown  to  blackish. 
Cut  surface :  Very  different  from  fine  Para,  the  non- 
fumigated  portions  being  dirty  white,  the  fumigated 
ones  brown  amber  color.  Odor :  Less  pronounced 
than  that  of  fine  Para,  it  having  an  odor  of  methyl- 
amine.  Adulteration :  Few  foreign  substances,  con- 


RAW    MATERIAL.  75 

sisting  generally  of  bark.  Moisture  like  fine  Para. 
Loss  in  working:  15  to  20  per  cent.  Less  strong 
than  fine  Para,  The  large  loaves  and^  biscuits  of 
fine  Para  are  cut  up  partly  in  the  trading  places  and 
partly  in  Para,  and  all  pieces  not  thoroughly  fumi- 
gated, and  containing  streaks  of  non-fumigated  rub- 
ber, are  sorted  out  as  entrefine. 

Nigger  heads;  Para  Sernamby ;  Sernamby  de  Bor- 
racha  ;  Sernamby  de  Jebe  ;  Cabeca  de  negro.  Origin  : 
Amazon  river.  Form  :  Comes  into  market  either  in 
large  blocks  or  mostly  in  irregular  pieces,  the  size 
of  the  hand,  which,  in  consequence  of  solid  packing, 
stick  together.  Appearance :  Black.  Cut  surface  : 
Yellowish  white  with  black  veins.  Odor :  Smells 
like  methylamine ;  sometimes  mouldy.  Adultera- 
tion: With  sand  and  non-elastic,  so-called  dead  rub- 
ber. Very  moist.  Loss  in  working :  20  to  40  per 
cent.  Lacks  resistant  power. 

Virgin  sheets  or  -Matto-grosso  Para  (Para  blanc). 
Origin  :  Province  Matto  Grosso,  Brazil.  Form  : 
Large  loaves  of  regular  shape,  about  two  feet  long, 
one  foot  wide  and  six  inches  thick  ;  smaller  loaves 
of  half  the  size.  Appearance  :  Pale  brown.  Cat  sur- 
face :  Straw  yellow,  with  greenish  marbling,  especi- 
ally on  the  edges.  Loss  in  working :  15  to  30  per 
cent.  Less  strong  than  brown  Para.  Like  Para,  it 
is  classed  :  Fine,  J  fine,  Sernamby. 

Ceara  scraps.  Origin :  Province  Ceara,  Brazil. 
Form :  Small  strips  or  tears  rolled  in  a  lump.  In 
consequence  of  being  solidly  packed  in  a  fresh  state, 
the  balls  stick  together  and  form  blocks  weighing 


76     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

up  to  330  Ibs.  Appearance:  Pale  and  dark  brown 
amber  color.  Out  surface:  Pale  amber  color  ;  when 
extended,  white  and  opaque.  Odor:  Very  dis- 
agreeable,  becoming  more  so  by  exposure  to  moist 
heat.  Adulteration :  Always  mixed  with  vegetable 
matter,  frequently  also  with  sand.  Up  to  15  per 
cent,  of  moisture.  Loss  in  ivorking :  20  to  25  per 
cent.;  with  inferior  qualities  mixed  with  sand,  up 
to  50  per  cent.  Quite  strong.  The  serum  of  Ceara 
rubber  can  be  quite  wTell  removed  by  mechanical 
pressure. 

Pernambuco  (Mongabeira).  Origin :  Province  of 
Pernambuco,  Brazil.  Form :  Rectangular  patches 
varying  in  size  ;  sometimes  5  feet  long,  2  feet  wide 
and  a  few  inches  thick.  Appearance:  Reddish 
orange-yellow  with  saline  efflorescence.  Cut  surface  : 
White  to  rose  color.  Numerous  holes  filled  with 
serum  containing  alum.  Loss  in  working :  40  to  60 
per  cent.  Has  but  little  elasticity ;  flabby ;  in 
little  demand  and  sometimes  is  used  only  on 
account  of  its  beautiful  color.  In  time  it  becomes 
hard  and  brittle. 

Maranham.  Origin  :  Province  Maranham,  Brazil. 
Appearance:  Smooth,  lustrous,  no  saline  efflores- 
cence. Cut  surface:  White  to  rose  color;  acquires, 
on  exposure  to  the  air,  a  beautiful  dark  wine-red 
color.  Loss  in  working  :  25  to  30  per  cent.  Stronger 
and  more  elastic  than  Pernambuco.  The  serum 
contains  sugar. 

BaJtia.  Origin:  Province  Bahia,  Brazil.  Form: 
Irregular  masses  or  large  patches  weighing  up  to 


.    RAW    MATERIAL.  77 

110  Ibs.  Appearance :  Reddish-orange.  Cut  surface  : 
AYhite  to  rose-color,  holes  with  serum  and  frequently 
with  non-coagulated  latex.  Adulteration:  Wood, 
vegetables,  sand,  clay.  Very  moist.  Loss  in  work- 
ing :  50  per  cent.  Of  inferior  quality ;  in  little 
demand. 

CartJiagcna  (Esquebo).  Origin  :  Columbia.  Form  : 
Large  balls  weighing  up  to  190  Ibs.,  formed  of 
patches  or  strips  which  are  folded  together  like 
Nicaragua  scraps.  Appearance:  Black.  Cut  sur- 
face: Brownish,  black,  greenish,  gray.  Odor:  Of 
methylamine  and  mould.  Adulteration:  Earth. 
Loss  in  work-ing:  25  to  60  per  cent.  It  is  quite  in 
demand.  The  good  quality  is  elastic,  but  that 
adulterated  with  earth  is  venr  dead. 

Ou/idad-BolivcLT,  Columbia  Virgen.  Origin:  Vene- 
zuela. Form:  Like  Para  rubber.  Appearance: 
Like  Para.  Cut  surface  :  Like  Para.  Odor:  Slightly 
fumigated.  Adulterations:  Often  mixed  with  the 
sap  of  Massaranda  and  Pindar.  Loss  in  ivorking : 
15  to  20  per  cent.,  according  to  quality.  Resem- 
bles Para  rubber  and  is  often  sold  as  such. 

Cayenne.  Origin :  French  Guiana.  Form,  ap- 
pearance and  cut  surface:  Like  Para  rubber.  Odor : 
Slightly  smoky.  Adulteration :  Quite  pure.  Loss 
in  working:  15  to  20  per  cent.  Value  equal  to 
Para. 

Peru  in  slabs,  also  called  caucho.  Origin:  Peru. 
Form  :  Large  blocks,  or  like  fine  Para.  Appearance  : 
Deep  black,  surface  granular.  Cut  surface:  Yellow  ; 
becomes  in  time  slate-color;  very  porous.  ' Adul- 


78     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

teration :  Much  sand  and  water.  Loss  in  working  : 
25  to  30  per  cent.  Very  elastic  and  highly  valued, 
though  the  color  is  not  liked.  By  boiling  in  water 
the  rubber  loses  its  black  color  and  becomes  dirty- 
white. 

Peruvian  balls,  Sernamby  de  Perou,  Sernamby  de 
CaucJw.  Origin:  Peru.  Form:  Like  niggerheads. 
Appearance :  Deep  black ;  surface  granular.  Cut 
surface:  Yellow;  becomes  in  time  slate-color ;  very 
porous.  Loss  in  working :  25  to  30  per  cent.  Ser- 
nambillo  (waste)  is  better  than  niggerheads,  as  it 
contains  less  water  and  is  less  porous. 

Guayaquil  (in  patches).  Origin  :  Ecuador.  Form  : 
Large  patches  up  to  3  feet  3  inches  in  length,  2J 
feet  wide,  and  about  f  inch  thick.  Appearance  : 
Blackish.  Cut  surface:  Black-green,  very  moist, 
with  many  water  bubbles.  Adulteration:  Very  im- 
pure ;  earth  and  vegetable  matter ;  much  water. 
Loss  in  working :  20  to  35  per  cent.  Partly  very 
elastic,  and  partly  adulterated  with  earth,  and  dead 
like  Carthagena  rubber. 

2.  CENTRAL  AMERICA.  Colon  and  Panama.  Origin: 
Ecuador,  Columbia.  Form:  Strips  about  4  inches 
m  diameter  and  up  to  10  feet  in  length.  Quality 
similar  to  Carthagena  rubber. 

Mexican  and  oth(r  Central  America  and  West  Indies 
sheets.  Origin :  Vera  Cruz,  Taumapilas,  Tabasco, 
Guerero,  Baraca,  Repic  Chiopas.  Form:  Sheets 
from  0.39  to  1.57  inches  thick,  and  2x  2J  inches  in 
length  and  width  ;  sometimes  balls  (marbles)  2  to 
2J  inches  in  diameter.  Appearance :  Black.  Cut 


RAW    MATERIAL.  79 

surface  :  Black,  brown,  yellow-greenish.  In  cutting 
a  sheet  a  brownish  liquor  sometimes  runs  out. 
Adulteration :  Sand,  earth,  leaves,  sometimes  splin- 
ters of  wood.  Loss  in  working :  12  to  15  per  cent. 
Extraordinarily  strong. 

Guatemala.  Origin:  Guatemala.  Form:  Sheets. 
Appearance  :  Black.  Cut  surface :  Black,  partly  yel- 
low-greenish, partly  brown  ;  contains  a  thick  fluid 
(non-coagulated  rubber).  Odor:  Very  character- 
istic. Adulteration:  Dirt,  bark,  earth.  Loss  in  work- 
ing :  25  to  45  per  cent.  Partly  strong  like  Guaya- 
quil, partly  softer. 

Nicaragua,  Mexican,  Ecuador  and  West  Indian  scraps. 
Origin :  Nicaragua,  Mexico,  San  Salvador,  Ecuador. 
Form :  Either  sausages  as  thick  as  an  arm  or  balls 

•of  at  least  the  size  of  a  head.  Sometimes  also  cubes 
2  to  2J  feet  long.  The  scraps  are  always  composed 
of  folded  or  rolled  strips,  waste  of  sheets  and  spon- 
taneously dried  drops.  Appearance:  Blackish.  Cut 
surface :  Usually  blackish  and  lustrous ;  sometimes 
yellowish,  but  soon  turns  black  on  exposure  to  the 
air.  Adulteration :  Slight  moisture,  some  cork, 
sometimes  sand.  Loss  in  working:  10  to  15  per 
cent.  Very  much  in  demand  ;  classes  next  to  fine 
Para. 

II.  AFRICAN  RUBBER.     Senegal  and  Bissao  balls. 

\  Origin :     Senegambia.    Soudan,    Bissagos     Islands. 

;  Form :  Partly  balls,  partly  sheets.  Appearance  : 
Black,  brown.  Cut  surface:  Rose  color,  white. 

\Adulteration:  Much  moisture,  sand,  bark,  dirt.    Loss 

\in  working:  25  to  50  per  cent.  Partly  very  strong, 
and  quite  in  demand. 


80     INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

Gambia  balls.  Origin:  Senegambia,  Bathurst, 
Bissagos  Islands,  Soudan.  Form:  Balls.  Appear- 
ance: Brownish,  white,  and  black.  Cut  surface: 
White  with  a  slight  tinge  of  rose-color.  Adultera- 
tion :  Moisture,  sand,  small  quantity  of  bark.  Loss 
in  working :  20  to  50  per  cent.  Pure,  dry  balls  are 
in  good  demand  ;  second  quality  is  not  much  liked. 

Casamanza  (Boalam).  Origin:  High  table-land 
on  the  right-hand  bank  of  the  Casamanza  river, 
Senegambia.  Form:  Like  Senegal  rubber.  Appear- 
ance: Dark  brown.  Cut  surface:  Grey  shading  into 
cream-yellow  and  reddish  ;  holes  with  much  sand. 
Odor:  Bad.  Adulteration:  Much  earth  and  sand. 
Loss  in  working :  40  per  cent.  Not  much  in  demand. 
Is  chiefly  brought  into  commerce  in  March. 

Casamanza  (Gambia).  Origin:  Left-hand  bank  of 
the  Casamanza  river.  Form:  Balls  weighing  10  to 
28  ozs.,  and  even  up  to  4  Ibs.  Appearance:  At  first 
white,  afterwards  red-brown.  Cut  surf  ace :  Concen- 
tric layers;  color,  red-brown  to  white;  Avhite  pre- 
dominates, but  on  exposure  to  the  air,  it  gradually 
acquires  the  red-brown  tone  of  the  surface.  Some- 
times concentric  veins,  black,  white  and  rose:color. 
The  rubber  prepared  by  chemical  disintegration,  by 
the  addition  of  vegetable  matter,  is  of  a  pale  amber 
color.  Adulteration  :  Small  quantity  of  foreign  sub- 
stances ;  quite  moist.  Loss  in  ivorking :  20  to  40  per 
cent.,  according  to  quality.  Quite  strong.  This 
rubber  would  be  excellent,  if  it  were  not  mixed  with 
other  varieties  of  latex,  the  black  rubber  contained 
therein  being  very  sticky,  and  having  an  injurious 
effect  upon  the  paler  rubber. 


RAW    MATERIAL.  81 

Sierra  Leone  Niggers,  Massai  Niggers.  Form  :  Balls. 
Appearance:  Red,  red-brown,  white.  Cut  surface; 
Red  and  glassy  brown,  white.  Odor:  None.  Adul- 
teration: Partly  very  pure,  partly  mixed  with  bark 
and  earth  ;  partly  dry,  partly  moist.  Loss  in  work- 
ing: 10  to  35  per  cent.  Red,  dry  balls  are  highly 
valued  ;  soft  and  moist  ones  are  not  liked. 

Sierra  Leone  twist :  Appearance:  Brown.  Cut  sur- 
face :  White.  Adulteration :  Partly  very  pure,  though 
frequently  adulterated  in  the  interior  with  earth  and 
bark  and  only  covered  with  good  strips.  Loss  in 
working:  18  to  35  per  cent.  Strong  and  highly 
valued. 

Liberia.  Origin:  Liberia.  Form:  Balls  and 
lumps.  Appearance:  White,  brown,  black.  Cut  sur- 
face: Of  the  balls,  white  and  rose  color;  of  the 
lumps,  green,  yellow  and  white.  Odor:  Of  the  balls, 
slight;  of  the  lumps,  very  bad.  Adulteration:  The 
balls  are  pure,  but  quite  moist ;  the  lumps  very 
moist.  Loss  in  working:  20  to  40  per  cent. 

Grand  Bassam.  Origin:  Ivory  Coast.  Form: 
Lumps.  Appearance :  Black.  Cut  surface :  Dark 
green,  partly  pale.  Odor  :  Bad.  Adulteration  :  Quite 
pure,  but  moist.  Loss  in  working  :  20  to  30  per  cent. 
Much  in  demand. 

Accrah.  Origin  :  Gold  Coast.  Appearance:  Brown, 
black.  Cut  surface:  Yellow,  brown.  Odor:  Very 
bad.  Adulteration:  Moist;  sometimes  mixed  with 
earth.  Loss  in  working :  30  to  45  per  cent.  A  good 
quality  of  this  rubber  is  much  in  demand  on 
account  of  its  purity,  but  the  soft  article  is  not 


82     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

liked.  Accrah  biscuits  pressed  on  the  coast  are  no 
longer  found  in  commerce. 

Niger  Niggers.  Origin  :  Niger  Territory.  Form  : 
Compressed  balls.  Appearance:  White,  red.  Cut 
surface :  White ;  root-rubber,  partly  red.  Odor  : 
Slight.  Adulteration :  Partly  pure,  but  moist ;  the 
root-rubber  contains  much  bark.  Loss  in  working  : 
20  to  45  per  cent.  The  white  balls  are  strong,  and 
in  demand  ;  the  root-rubber  is  resinous  and  soft. 

Gaboon  Balls.  Origin  :  French  Congo.  Form  : 
Large  and  small  balls.  Appearance:  Black  and 
gray.  Out  surface :  Of  the  large  balls,  rose-color, 
blue  and  red ;  of  the  small  ones,  grey,  white  and 
green.  Odor:  Bad.  Adulteration:  Bark,  sand,  very 
moist.  Loss  in  working :  27  to  40  per  cent.  The 
large  balls  are  strong  and  highly  valued,  but  the 
small  ones  are  soft  and  in  little  demand. 

Gaboon  Tongues.  Form :  Small,  oblong  balls. 
Cut  surface:  White  and  gray.  Adulteration:  Sandy 
on  the  outside,  moist,  partly  calcareous.  Loss  in 
working :  35  to  45  per  cent:  In  little  demand. 

Kassai  rouge.  Origin :  Congo  State.  Form  : 
Small  balls,  ten  of  them  being  stuck  together  so  as 
to  form  a  short  pig-tail.  Appearance:  Ked.  Adul- 
teration :  Very  few  impurities.  Loss  in  working  : 
6  to  8  per  cent.  Very  sinewy.  Is  considered  the 
best  quality  of  the  Congo  varieties. 

Kassai  noir.  Origin :  Congo  State.  Form :  Pig- 
tails. Appearance :  Black.  Adulteration :  Fre- 
quently mineral  and  volatile  substances.  Of  less 
value  than  Kassai  rouge. 


RAW    MATERIAL.  83 

Kassa'i  noir  in  balls.  Origin  :  Congo  State.  Form  : 
Pieces  of  irregular  size  stuck  together  to  form  balls. 
Appearance :  Black.  Adulteration:  Neither  sand 
nor  wood,  but  considerable  quantities  of  volatile, 
fermenting  substances. 

Kassa'i  strips.  Origin :  Congo  State.  Form : 
Balls  stuck  together.  Adulteration:  Volatile,  fer- 
menting substances.  Quite  strong. 

Upper  Congo  (common).  Origin :  Congo  State. 
Form:  Balls  stuck  together.  Adulteration:  Bark 
and  about  8  per  cent,  water.  'Loss  in  working  : 
About  15  per  cent.  Strong.  This  is  the  variety 
first  imported  from  Congo. 

Upper  Congo  (white).  Origin:  Congo  State.  Form: 
Balls.  Cut  surface:  White.  Adulteration:  Very 
pure,  6  to  8  per  cent,  water.  Very  strong. 

Equator.  Origin :  Congo  State.  Form :  Balls 
stuck  together.  Adulteration  :  But  few  impurities, 
5  to  7  per  cent,  water.  Strong,  good  quality. 

Lopari.  Origin:  Congo  State.  Form:  Balls. 
Adulteration  :  Volatile  and  fermenting  substances. 
Very  elastic ;  as  much  in  demand  as  Equator. 

llusira.  Origin  :  Congo  State.  Form :  Balls. 
Highly  valued,  almost  as  much  as  Equator. 

Aruwimi,  Mongala,  Bumba.  Origin:  Congo  State. 
Form :  Balls  weighing  up  to  11  Ibs.  Odor:  Very 
bad  and  penetrating.  Adulteration  :  Up  to  35  per 
cent,  of  fermenting  substances.  Loss  in  working  : 
Large.  Quality,  good. 

Uelle.  Origin :  Congo  State.  Form :  Sheets 
weighing  up  to  22  Ibs.  Appearance:  White.  Adul- 


84  INDIA    RUBBER,  GUTTA    PERCH  A,  BALATA. 

teration :  Quite  pure ;  volatile,  but  only  exception- 
ally fermenting,  substances. 

Longer  Congo  (thimbles).  Origin :  Congo  State, 
Angola.  Form :  Square  cut  pieces.  Appearance  : 
Quality  I.,  red  and  black  ;  Quality  II.,  black  and 
reddish.  Cut  surface:  Quality  I.,  red  and  black; 
Quality  II.,  red.  Adulteration:  Quality  I.,  pure, 
sometimes  sandy  ;  Quality  II.,  contains  bark,  and 
in  some  instances  earth.  Loss  in  working :  I.,  12  to 
20  per  cent  ;  II.,  27  to  45  per  cent.  Quality  I., 
strong  though  partly  resinous;  II.,  when  dry  much 
in  demand,  but  not  liked  when  wet. 

Luvituku.  Origin :  Lower  Congo.  Form  :  Balls. 
Composition  and  quality  like  Congo  thimbles. 

Loanda  thimbles.  Origin:  Angola.  Form  :  Thim- 
bles or  cubes,  0.19  to  1.18  inches  in  size.  Appear- 
ance: Slate-gray.  Cut  surface  :  Lustrous,  slate-gray 
with  white  dots.  Odor :  Offensive,  like  dry  Congo 
rubber.  Adulteration :  No  foreign  substances,  though 
recently  attempts  at  adulteration  have  been  made. 
Loss  in  working :  15  to  20  per  cent.  Inclines  to 
become  soft  and  smeary,  and  should  be  kept  in  a 
cold  room. 

Loanda  Niggers.  Origin  :  Angola  (Loanda).  Form  : 
Balls  strung  together  in  chains.  Appearance  :  Qual- 
ity I.,  red  and  black;  II.,  reddish.  Cut  surface:  I., 
red  and  black;  II.,  red.  Odor:  Slight.  Adultera- 
tion :  Quality  I.,  pure  and  dry  ;  II.,  much  bark,  and 
in  some  cases  sand.  Loss  in  working:  L,  S  to  15 
per  cent.,  II.,  20  to  27  per  cent.  Quality  I.  is 
strong  and  much  in  demand :  Quality  II., 


RAW    MATERIAL.  85 

strong,  but  quite  in  demand  when  dry  and  not  oxi- 
dized ;  resinous. 

Angola  Niggers  or  Nigger-heads.  Origin  :  Angola. 
Form:  Balls  of  irregular  form,  1.18  to  2  inches  in 
diameter.  Appearance :  Reddish-brown.  Cut  sur- 
face :  Reddish-brown,  almost  transparent  towards 
the  centre  ;  very  soft,  but  becomes  hard  when  ex- 
posed for  a  fe\v  days  to  the  air.  Adulteration  :  Quite 
moist ;  small  quantity  of  portions  of  plants.  Loss  in 
working :  20  per  cent.  Less  strong  than  Loanda 
Niggers;  quite  sticky. 

Benguela  Niggers.  Origin  :  Angola  (Benguela  and 
iMossamedes).  Form:  Balls  strung  together  to 
chains  ;  also  small  sausages.  Appearance  :  Reddish. 
Out  surface  :  Red.  Adulteration  :  Much  bark.  Loss 
in  working :  20  to  25  per  cent.  When  dry  the  rub- 
ber is  much  sought  after,  but  the  fresh  article,  pale 
inside,  which  readity  oxidizes,  is  not  in  demand. 

Mozambique  Marbles.  Origin:  Mozambique. 
Form:  Small  balls  pressed  together.  Appearance: 
Black  and  reddish.  Cut  surface:  Red,  in  isolated 
cases,  white.  Adulteration :  Much  bark ;  partly 
sand  ;  moist.  Loss  in  working :  30  to  40  per  cent. 
Soft,  of  inferior  quality  ;  root-rubber. 

Mozambique  Balls.  Origin:  Mozambique,  Ger- 
man East  Africa.  Form :  Smaller  and  larger  balls. 
Appearance :  Brown  and  rose-color.  Cut  surface : 
Red,  brown,  rose-color,  W7hite.  Odor :  None.  Adul- 
teration :  Quality  Ia  Ia  is  very  pure  and  dry  ;  infer- 
ior quality  contains  sand  and  portions  of  plants,  and 
is  moist.  Loss  in  Working :  8  to  35  per  cent.  The 


86     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

best  glassy  balls  which  are  cut  piece  by  piece  in 
their  place  of  origin  are  much  in  demand  on  ac- 
count of  their  excellent  quality  and  small  loss  in 
working.  Inferior  qualities  arefalso  in  demand. 

Mozambique  Spindles.  Origin :  Mozambique. 
Form :  Spindles.  Appearance :  Brown  and  red. 
Cut  surface :  Red  and  brownish  ;  in  isolated  cases, 
black.  Odor:  None.  Adulteration:  Bark  and  sand. 
Loss  in  Working:  12  to  27  per  cent.  When  un- 
adulterated much  in  demand,  as  the  rubber  is  very 
strong  and  the  loss  in  working  small. 

Madagascar,  black.  Origin :  Madagascar.  Form  : 
Large  round  pieces.  Appearance :  Black.  Gut  sur- 
face: White,  rose-color,  yellow,  green.  Odor: 
Offensive.  Adulteration :  Earth,  portions  of  plants, 
very  moist.  Loss  in  working:  30  to  45  per  cent. 
Suitable  for  the  manufacture  of  hard  rubber. 

Madagascar,  pinky.  Appearance:  Brown  and 
black.  Out  surface :  Rose-color,  white.  Adultera- 
tion: Pure,  but  moist.  Loss  in  working:  25  to  40 
per  cent.  Highly  valued.  Not  very  strong,  but 
elastic. 

Madagascar  Niggers.  Form :  Large  balls.  Ap- 
pearance :  Black  and  yellow.  Cut  surface :  Brown- 
ish, white,  black  and  yellow.  Odor:  Slight. 
Adulteration :  Dry,  but  generally  much  adulterated 
with  earth.  Loss  in  working :  20  to  60  per  cent. 
The  yellow  West  Coast  Niggers  are  frequently  very 
soft,  but  sometimes,  like  the  East  Coast  Niggers, 
are  very  strong,  and  are  then  highly  valued. 

III.  ASIATIC   RUBBER.      Assam.    Origin:    North 


RAW    MATERIAL.  87 

West  Bengal  (Brahmapootra).  Form:  Lumps 
weighing  up  to  5J  ozs.  which  adhere  firmly  to  the 
cover  as  this  rubber  becomes  rapidly  viscous  and 
smeary.  Appearance:  Brown.  Cut  surface:  Dark, 
sometimes  gray,  sometimes  reddish  with  white 
nearly  transparent  patches.  Adulteration:  Moist 
sand,  wood,  earth.  Loss  in  working :  25  to  40  per 
cent.  Was'  formerly  much  liked,  but  is  now  less 
highly  valued  because  it  has  deterioarated  in  qual- 
ity. It  is  disappearing  from  the' market. 

Rangoon.  Origin:  Burma,  Cochin-China,  Anam, 
Tonkin.  Form:  Irregular  masses.  Appearance: 
Very  dark  brown.  Cut  surface :  Lustrous,  white, 
red  and  black  marbled.  Adulteration :  Always  con- 
tains wood.  Loss  in  working :  20  per  cent.  Less 
valued  than  the  preceding  variety. 

Penang.  Origin:  Sumatra  and  other  Sunda 
islands.  Form:  Large  bisected  lumps  and  balls. 
Appearance:  Red,  brown.  Cut  surface:  Red,  rose- 
color,  whitish.  Adulteration:  Wood,  small  quantity 
of  earth,  partly  moist.  Loss  in  working:  15  to  30 
per  cent.  A  good  dry  quality  is  highly  valued ; 
the  moist,  sticky  article  is  not  in  demand. 

Ceylon.  Origin  :  Ceylon.  Form  :  Irregular  cubes 
about  4  inches  large.  Appearance:  Black.  Cut 
surface:  Dark  brown,  pale  brown,  and  transparent. 
Adulteration:  Sand,  earth.  Loss  in  working:  20  to 
25  per  cent.  Quite  strong. 

Java  and  Padong.  Origin :  Java,  Sumatra,  and 
other  Sunda  islands.  Form  :  Large  bisected  lumps 
and  balls.  Appearance :  Red,  brown.  Cut  surface : 


88     INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

Red,  glassy,  rose-color,  white.  Odor:  Slight.  Adul- 
teration: Wood,  small  quantity  of  earth,  partly 
moist.  Loss  in  working  :  12  to  30  per  cent.  Good, 
dry  ware  is  much  in  demand  ;  the  moist,  sticky 
article  is  not  valued. 

Borneo.  Origin  :  Borneo.  Form :  Large  lumps, 
flat  pieces,  and  balls.  Appearance :  Black.  Cut 
surface:  White,  rose-color,  blue,  green.  Adulteration  : 
Earth,  wood,  portions  of  plants  ;  very  moist.  Loss 
in  working :  Quality  I.,  35  to  45  per  cent.;  II.,  35  to 
50  per  cent.;  III.,  40  to  00  per  cent.  Quality  I., 
very  strong  and  beautiful ;  II.,  partly  soft  ;  III., 
frequently  contains  dead  pieces. 

Borneo  Djambes.  Origin:  Sumatra.  Form:  Balls 
and  sheets.  Appearances :  Brown-red.  Out  surface  : 
Greenish- red.  Adulteration  :  Alumina,  much  water. 
Loss  in  working :  45  per  cent,  and  over.  But  little 
in  demand  on  account  of  the  impurities. 

Borneo  (Ben  Koclen).  Form:  Thin  sheets.  Ap- 
pearance: Brown.  Cut  surface:  Inside  white.  Adul- 
teration: Quite  pure.  Good  quality. 

IV.  AUSTRALIAN  RUBBER.  New  Caledonia.  Origin  : 
New  Caledonia.  Form :  Biscuits  like  Para  rubber 
weighing  13  to  22  pounds  ;  also  balls.  Appearance  : 
Pale  and  brown,  sometimes  a  black  tinge.  Cut 
surface :  White  veined.  Odor :  Smoky.  Adultera- 
tion :  Very  pure.  Loss  in  working:  12  to  20  per 
cent.  A  very  good  quality,  when  not  mixed  with 
other  varieties.  Somewhat  resinous.  Has  been  but 
recently  introduced  in  the  European  market. 

Statistics.     As  regards  the  statistics  of  the  rubber 


RAW    MATERIAL. 


89 


trade,  there  is  the  broad  fact  that  the  world's  re- 
quirement in  raw  rubber  is  fast  rising  from  120  to 
130  million  pounds  a  year,  in  confirmation  of  which 
we  give  an  estimate  of  the  world's  production  and 
consumption  of  rubber,  supported  by  such  detailed 
figures  as  are  available. 


Production. 
Brazil,  Peru,  etc.  (Para).   .   . 

Brazil,  Ceara,  etc 

Brazil,  Mangabeira     .... 

Guiana 

Bolivia 

Rest  of  South  America  .  .  . 
Central  America  and  Mexico 
Java,  Borneo  and  Eastern 

Archipelago 

East  and  West  Africa  .  .  .  . 
Madagascar  and  Mauritius  . 

India  and  Burma 

Ceylon 

Australia  . 


Cwt. 

450,000 

94,000 

65,000 

6,000 

30,000 

40,000 

50,000 

20,000 

480,000 

10,000 

8,000 

150 


Cwt 1,250,150 


Consumption.  Cwt. 

America  (United  States  and 

Canada) 400,000 

United  Kingdom  and  De- 
pendencies save  Canada    .  450,000 

Continent  of  Europe 400,000 


Cwt 1,250,000 


The  principal  market  for  crude  rubber  in  Europe 
is  Liverpool,  which  of  all  kinds  of  rubber 


I 

In 

Imported, 
Tons. 

Sold, 
Tons. 

Remp.ined 

in  stock, 
Tons. 

In 

Imported, 
Tons. 

Sold, 
Tons. 

Remained 
in  stock, 
Tons. 

1887 

7330 

5890 

1440 

1893 

11330 

9830 

1500 

1888 

7900   6485 

1415 

1894 

11560 

16285 

1275 

1889 

8750 

7760 

990 

1895 

13720  j  12640 

1080 

1890   9900 

8610 

1290 

1896 

17300 

15640 

1660 

1891 

10680   9480 

1200 

1897 

15365 

14285 

1086 

1892 

10400 

8950 

1450 

1 

London,    Hamburg,    Rotterdam,    Antwerp,   Bor- 
deaux and  Marseilles  also  import  rubber. 


90 


INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 


The  importance  of  the  London  market  compared 
with  that  of  Liverpool  is  shown  in  the  annexed 
table : 


In 

Imported, 
Tons. 

Sold, 
Tons. 

Remained 
in  stock. 
Tons. 

1 
In 

Imported, 
Tons. 

Sold, 
Tons. 

Remained 
in  s-tock, 
'1  ons. 

1887 

2400 

1385 

1015 

1893 

1720 

1280 

440 

18S8 

2280 

1313 

977      1894 

1935 

1485 

450 

1889 

1660 

1050 

610 

1895 

1720 

1260 

460 

1890 

1893 

1247 

646 

1896 

1579 

1235 

1137 

1891 

1900 

1310 

590 

1897 

460 

344 

320 

1892 

1740 

1255 

485    || 

The  principal  European  countries  together  with 
the  United  States  imported  rubber  in  1896-7  to  the 
following  approximate  amount  and  value : 


COUNTRIES. 

Years. 

Quantity. 
Tons. 

Value. 
£. 

Great  Britain 

1896 

21  558 

4  991  ]  99 

1896 

5  177 

1,111  256 

Germany       

1897 

8  436 

2  320  150 

Belgium     

1897 

2  ^36 

545  835 

Holland     

1897 

1  672 

141  667 

Austria-Hungary   .   .   . 
United  States  

1897 
1897 

2,109 
18*821 

811,415 
4  514  587 

60,009 

14,436,032 

RAW    MATERIAL.  91 

Prices  of  India  Rubber. 

(From  S.  Figgis  &  Co.'s  Fortnightly  Price  Current, 
June  15,  1899.) 

s.  d.      s.  d. 

India  rubber   ......  Red  hard  clean  ball    .........  3    2  to  3  6 

f  White  softish  ball  .......   .   .   .  2    8  to  3  0 

East  African  Ports,  Zan-  [  Unripe  root  ............     1    2  to  2  1 

zibar  and  Mozambique  -  Liver  and  Lamu  ball  ........  2    8  to  3  0 


Coast 


ausage  ordinary  to  fine  ......  3    0  to  3 


L  Sausage  without  sticks  .......  3    3  to  3    6 

India  rubber,  Assam  .   .  J  Good  to  fine  ............  2    8  to  3    3 

•  Common  foul  and  middling  .   .   .   .  1  10  to  2    5 

Rangoon   .......  Fair  to  good  clean       .......  2  11  to  3    1 

Madagascar     Tamatave,  f  Good  to  fine  pinky  and  white    ...  3    2  to  3    4% 

Majunga  and  Nossibe.  (  Fair  to  good  black   .........  1    8  to  2    (5 

India  rubber,  Borneo  .   .  J  Fair  to  fine  nigger  ball  .......  1    5  to  2    7 

<  Fair  to  fine  clean  ..........  1    9  to  2    5 

f  Mixed,  part  dead  .......  1    1  to  1    6% 

Java,    Singapore    and      j  Good  to  fine  red  selected     .....  2    8  to  3    1 

Penang  ........   j  Mixed,  part  soft       .........  1    7  to  1  10% 

[Pickings,  part  common  ......  •.  0    9  to  1    3 


CHAPTER  II. 

MECHANICAL  TREATMENT  OF  CRUDE  RUBBER. 

RUBBER  in  the  crude  state  finds  but  little  appli- 
cation, and  besides  the  pieces  used  for  erasing  pencil 
marks,  which  are  simply  cut  with  a  knife  from  Para 
biscuits,  it  is  occasionally  employed  for  billiard 
cushions,  and  in  the  form  of  square  non-vulcanized 
threads.  All  other  articles  serving  for  thousands 
of  diverse  purposes,  require  more  or  less  manipu- 
lation. 

In  the  industrial  working  of  rubber,  the  first 
matter  to  be  attended  to  is  the  removal  of  the 
various  impurities  present  in  the  crude  material. 
These,  as  previously  mentioned,  are  in  some  cases 
natural  products,  which  have  originated  with  the 
rubber,  while  in  other  cases  they  owe  their  presence 
to  careless  collection  or  to  adulteration.  The  ad- 
mixtures may  range  from  fragments  of  bark  or 
wood  to  stones  or  large  lumps  of  clay,  such  as  are 
sometimes  introduced  into  niggerhead  rubber,  hay 
or  a  similar  substance  being  also  placed  inside  to 
make  the  mass  about  equal  in  specific  gravity  to 
the  genuine  article.  Alum  and  sulphuric  acid  are 
often  employed  to  effect  the  coagulation  of  the 
rnilky  juice,  and  traces  of  them  remaining  in  the 
rubber  appear,  in  some  instances,  to  work  mischief. 

(92) 


TREATMENT  OF  CRUDE  RUBBER.        93 

The  operation  of  purifying  the  crude  rubber  con- 
sists in  softening  and  superficial  washing,  cutting 
up,  rolling  or  actual  washing,  and  drying. 

In  manipulating  the  crude  material  it  is  advis- 
able to  use  only  rubber  of  one  and  the  same  variety 
at  one  time,  as  different  kinds  demanded  different 
treatment. 

Generally  speaking,  American  rubber  requires 
less  manipulation  than  the  East  Indian  or  African 
article.  Hence  if  the  two  kinds  mixed  in  one  lot 
were  to  be  worked,  the  first  would  be  purified  while 
the  other  would  require  still  further  treatment. 

Softening  or  superficial  washing.  The  rubber  as 
brought  from  the  store-room  is  too  solid  and  hard 
to  be  worked,  and  the  ordinary  temperature  of  our 
climate  is  not  sufficient  to  impart  to  it  the  requisite 
softness.  Hence  it  must  be  artificially  softened, 
which  is  the  most  simple  of  all  the  manipulations. 
The  rubber  is  placed  in  water  heated  by  steam,  in 
which  it  remains  from  3  to  24  hours,  according  to 
requirement.  Wooden  vats  or  iron  tanks  are  most 
suitable  for  the  purpose.  For  certain  varieties  it  is 
recommended  to  add  caustic  soda  to  water,  but  the 
use  of  acidulated  water  should  be  avoided. 

( 'idting  up.  The  lumps  of  the  softened  crude 
rubber  are  then  cut  into  slices  by  means  of  a  sharp 
knife,  generally  by  hand,  as  thus  any  large  stones  or 
other  foreign  substances  can  be  removed.  However, 
cutting  machines  are  frequently  used,  the  older 
kinds  resembling  somewhat  a  straw  cutter.  Sharp 
knife  blades  were  set  obliquely  on  the  spokes  of  a 


94 


INDIA    RUBBER,  GUTTA    PERCHA,  BALATA. 


wheel  which  revolved  rapidly.  The  lumps  of  rubber 
to  be  cut  up  were  pressed  by  a  lever  against  the 
knives,  which  were  kept  wet  with  water.  Although 
such  a  machine  is  of  quite  simple  construction  and 
works  satisfactorily,  it  has  the  disadvantage  of  re- 
quiring frequent  repairs.  For  instance,  if  the  edge 
of  the  knife  hits  a  pebble  in  the  rubber,  it  becomes 
notched,  and  then  tears  rather  than  cuts,  and  hence 
the  knives  must  be  frequently  ground..  To  prevent 
constant  interruptions  of  the  work,  the  knives  should 
be  so  arranged  that  they  can  be  readily  taken  off, 
and  replaced  by  newly  ground  knives. 

An  improvement  in  cutting  machines  is  shown  in 

FIG.  1. 


Fig.  1.  In  consists  of  an  iron  drum,  a,  24  to  28 
inches  in  diameter  and  8  inches  wide,  with  a 
large  number  of  obliquely  set  knives,  b  b,  which 
project  slightly  above  the  periphery,  and  are 
arranged  in  rows,  as  seen  in  the  illustration. 
The  lump  of  rubber  is  pressed  against  the  knives 


TREATMENT  OF  CRUDE  RUBBER.        95 

by  a  lever  arrangement  consisting  of  the  lever 
d,  upon  which  the  workman  stands,  and  a  joint 
lever,  c,  with  its  fulcrum  at  k,  and  the  upper 
blade-shaped  end,  gy  presses  the  rubber  against  the 
knives.  A  counter  weight,  h,  brings  the  lever  back, 
the  manipulation  of  which  is  facilitated  by  the 
handle  i.  The  drum,  which  revolves  with  great 
velocity,  tears  the  rubber  into  small  chips.  Previous 
softening  of  the  rubber  is  not  required  in  working 
with  this  machine. 

Rolling  or  washing.  This  is  the  most  essential 
part  of  the  operation  of  purifying  rubber,  its  object 
being  to  remove  the  foreign  substances  enclosed  in 
the  mass.  Fig.  2  shows  a  machine  most  generally 
used  for  the  purpose.  It  consists  of  two  massive 
cast  iron  rolls  lying  horizontally  alongside  each 
other,  and  revolving  with  unequal  velocity  towards 
the  inside.  The  surfaces  of  the  rolls  are  either  corru- 
gated or  smooth,  but  the  position  of  the  two  rolls  is 
always  the  same.  In  English  and  American  facto- 
ries corrugated  rolls  are  preferred,  since  the  corru- 
gations facilitate  purification  by  penetrating  into 
the  rubber  and  grinding  up  the  foreign  substances. 
As  shown  in  the  illustration,  the  rolls  rest  in  a 
strong  iron  frame.  The  bearings  of  the  back  roll 
rest  laterally  against  the  frame,  and  those  of  the 
front  roll  against  two  screws.  The  revolution  of 
the  rolls,  each  by  itself,  is,  as  a  rule,  effected  by 
means  of  cog-wheels  from  a  principal  axis  under  the 
floor,  though  there  are  also  machines  in  which  the 
revolution  is  directly  transmitted  from  one  roll  to 


96     INDIA  RUBBER,  GUTTA  PERCHA, BALATA. 

the  other.  However,  the  rolls  always  revolve  to- 
wards the  inside.  By  means  of  the  screws  on  the 
front  side  of  the  frame,  the  rolls  can  be  set  closer  or 
further  apart.  Underneath  the  rolls  is  a  sheet-iron 
reservoir  covered  with  a  perforated  plate.  Over  the 
rolls,  about  1  to  1  \  feet,  exactly  above  their  point  of 
contact,  is  a  perforated  pipe,  through  which  during 

FIG.  2. 


the  work  cold  water  is  constantly  discharged,  which 
runs  off  through  a  pipe  in  the  sheet-iron  reservoir 
mentioned  above.  The  rubber  to  be  washed  is  fed 
by  the  hand  in  very  small  quantities,  according  to 
the  size  of  the  machine,  between  the  revolving  rolls, 
the  cock  on  the  water  pipe  being  at  the  same  time 
opened.  The  rubber  is  caught  by  the  rolls,  crushed, 
torn  and  pulled  apart,  while  the  water  penetrates 


TREATMENT  OF  CRUDE  RUBBER.        97 

into  all  the  interspaces,  washing  away  the  particles 
of  bark,  fibres  and  earthy  constituents,  and  remov- 
ing also  all  other  crushed  foreign  substances.  After 
repeatedly  passing  through  the  rolls,  the  product 
obtained  is  a  long,  blotting-paper  like  sheet  with  a 
wrinkled  surface,  which  shows  numerous  small 
elevations  separated  from  each  other  by  small  cavi- 
ties, and  which  gives  a  characteristic  appearance  to 
rubber  in  this  state. 

Each  machine  is  attended  by  one  workman.  The 
occupation  is  not  without  clanger,  since  by  the 
slightest  inattention  the  fingers  may  get  between 
the  rolls,  and  if  the  machine  is  not  instantly  stopped, 
the  hand  and  arm  will  be  drawn  in.  Hence  every 
machine  should  be  provided  with  a  promptly  acting 
disengaging  gear.  Such  an  arrangement  will  be 
described  later  on  in  speaking  of  masticating  rolls. 

The  size  of  the  machines  varies  very  much. 
However,  as  a  rule,  the  rolls  are  2  to  2J  feet  long, 
with  a  diameter  of  1 J  to  1 J  feet,  and  the  velocity  is 
8  to  12  revolutions  per  minute  for  one  roll,  and  3 
to  4  for  the  other. 

Some  factories  use  hollow  rolls  so  arranged  that 
they  can  occasionally  be  filled  with  steam,  and  in 
this  case  the  machine,  as  "will  be  explained  later  on, 
serves  for  two  operations.  For  large  factories  this 
arrangement,  however,  is  not  suitable. 

All  varieties  of-  rubber  cannot  be  Avashed  with  the 

same    facility.     Para   rubber,    containing   the  least 

impurities,  is  washed  most  quickly.     The  so-called 

fat  or  pitchy  varieties  yield  the   foreign  substances 

7 


98     INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

with  difficulty,  and  frequently  the  impurities  are  so 
firmly  fixed  in  the  mass  that  they  cannot  be  re- 
moved. Naturally  very  dry  varieties  of  rubber  can- 
not always  be  rolled  into  sheets  or  leaves,  as  they  do 
not  hold  together,  and  in  many  cases  the  rubber 
comes  in  small  pieces  from  the  machine.  If  wash- 
ing is  thoroughly  done,  the  sheet  contains  no  foreign 
substances,  except  water,  which  is  removed  by 

Drying,  For  tins  purpose  the  rubber  is  suspended 
over  iron  wires  or  wooden  poles  either  in  lofts  where 
it  is  exposed  to  the  air,  or  "in  drying  chambers 
which  can  be  heated  to  122°  to  140°  F.  This 
operation  requires  no  special  attention,  but  it  may 
be  said  that  fat  or  pitchy  varieties  require  a  low 
temperature  for  drying,  since  by  drying  at  a  high 
temperature  their  natural  defects  would  become 
still  more  prominent.  The  sheets  would  tear,  fall 
upon  the  floor  and  stick  together  in  balls  from 
which  the  water  would  evaporate  very  slowly  and 
with  great  difficulty.  Not  very  adhesive  varieties 
of  rubber  which  come  in  small  pieces  from  the 
washing  rolls  are  dried  upon  frames. 

For  drying  it  is  of  great  importance  whether  the 
room  is  more  or  less  light,  or  more  or  less  exposed 
to  the  air.  A  good  draught  facilitates  drying 
extraordinarily,  and  in  summer  the  operation  is 
finished  in  a  few  days.  More  time  is,  of  course, 
required  in  winter,  and  steam  heat,  carefully  ap- 
plied, is  then  of  great  use.  The  injurious  effect  of 
strong  light  upon  rubber  has  previously  been  re- 
ferred to,  and  hence  the  darker  the  drying  room, 
the  better. 


TREATMENT  OF  CRUDE  RUBBER.        99 

When  dry  the  rubber  is  taken  from  the  wires  or 
frames,  folded  like  cloth  or  rolled  together  in  pack- 
ages. It  is  then  brought  into  a  special  store  room 
where  it  is  protected  from  light  and  moisture  and 
kept  until  required  for  further  working. 

By  washing  and  drying  the  rubber  has  lost  a 
portion  of  its  weight,  the  difference  between  the 
gross  weight  of  the  crude  material  and  the  net 
weight  of  the  purified  dried  article  constituting  the 
loss  in  washing, 

The  annexed  table  shows  the  loss  with  some 
varieties,  though  it  is  difficult  to  give  definite 
figures  : 

Para 10  to  16  per  cent. 

Sernamby      .         .         .         .     15  "  35       " 
Mozambique  (spindles) ..         .     10  "  25       " 

(rose  color,  balls)   15  "  25 
Columbia       .         .         .         .     10  "  25       " 
Peru  (sheets)  .         .         .     30  "  40 

Guatemala     .         .         .         .     20  "  40 
Assam  .         .         .         .         .     10  "  30       " 

Java 20  "  35       " 

Borneo  .         .         .         .     10  "  45       " 

Guayaquil     .         .  .     30  "  50 

Senegal-Soudan     .         .         .20  "  35       " 
It   frequently    happens   that    two   shipments   of 
rubber  which  are  sold  as  the  same  variety   vary 
very  much  as  regards  loss  in  washing,  the  difference 
amounting  sometimes  to  as  much  as  25  per  cent. 

Further  working  of  the  washed  crude  rubber.  For 
the  purpose  of  further  manipulation,  the  washed 


100    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

sheets  when  dry  have  again  to  pass  through  between 
rolls,  this  time,  however,  without  the  use  of  water. 
The  rolls  are  hollow  and  heated  by  steam.  Accord- 
ing to  the  purpose  intended,  they  act  either  exclu- 
sively as  a  masticating  machine,  or  at  the  same 
time  as  a  masticating  and  mixing  machine,  their 
construction  being,  however,  the  same  in  either 
case.  The  machine  consists  of  two  rolls  each  about 
2  to  3  feet  long  and  16  to  20  inches  in  diameter, 
which  revolve  one  towards  the  other.  As  a  rule 
they  are  placed  one  alongside  the  other,  the 
arrangement  of  one  above  the  other  being  the 
exception  and  seldom  used  at  the  present  time.  In 
all  other  respects  they  closely  resemble  the  washing- 
rolls.  The  accompanying  illustration,  Fig.  3,  a,  b 
and  c,  shows  mixing  rolls  from  the  front,  side  and 
above.  It  also  shows  the  disengaging  gear  men- 
tioned on  page  97.  The  latter  has  the  advantage 
that  the  workman  can  engage  it  with  one  hand 
by  pulling  a  rope,  even  if  the  other  hand  should 
have  been  drawn  in  between  the  rolls.  Its  con- 
struction and  mode  of  operation  are  as  follows  : 
The  rope  F  is  carried  tight  over  the  pair  of  rolls 
from  one  standard  of  the  frame  to  the  other,  then 
over  a  pulley  G  to  the  latch  /.  The  latter  is  pro- 
vided with  a  catch  which  acts  on  the  lever  with  the 
counterweight  K.  If  now  the  instant  disengage- 
ment of  the  rolls  becomes  necessary,  the  workman 
pulls  the  rope  F.  By  this  pull  the  latch  /is  drawn 
upwards,  whereby  the  counterweight  K  is  released  ; 
K  falls  down  and  the  piece  M,  which  is  rigidly  con- 


TKEATMENT  OF  CRUDE  RUBBER. 


101 


nected  with  the  lever,  makes  a  turn  upwards,  slides 
along  on  the  surface  of  the  screws  and  disengages 
the  clutch  coupling,  whereby  the  disengaging  gear 
is  pushed  to  the  left  side,  and  the  rolls  are  brought 
immediately  to  a  standstill.  Reengaging  is  effected 
as  follows :  The  lever  which  carries  the  counter- 
weight K  is  lifted  by  means  of  the  rope  fastened  to 


Fig.  3. 


it,  the  latch  is  again  engaged  and  the  disengaged 
gear  L  pushed  to  the  right. 

While  up  to  this  point  the  treatment  of  all  vari- 
eties of  crude  rubber  for  further  manipulation  is  the 
same,  from  this  stage  on  it  varies  according  to 
whether  pure  unmixed  mass  for  the  manufacture  of 
fine  cut  sheets  is  to  be  prepared,  or  a  mixed  mass 
which  for  certain  purposes  must  receive  necessary 


102    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

admixtures.  In  the  first  case  the  rolls,  as  pre- 
viously mentioned,  serve  exclusively  as  macerating 
rolls,  and  in  the  latter,  simultaneously  as  macerat- 
ing and  mixing  rolls. 

Fine-cut  sheets  form  an  important  article  of  com- 
merce, and  for  their  manufacture  only  the  best 
quality  of  Para  rubber  should  be  used.  The  sheets 
of  rubber,  without  the  addition  of  any  foreign  sub- 
stance, are  worked  in  the  macerating  rolls  until  a 
homogenous  mass  free  from  air  is  obtained,  which 
comes  from  the  machine  in  the  form  of  rolls.  The 
latter  are  subjected  to  strong  pressure  in  a  hydraulic 
press,  whereby  larger  and  more  homogeneous  blocks 
are  obtained,  which  are  stored  for  several  months  at 
a  varying  temperature  by  which  means  their  text- 
ure becomes  closer  and  their  quality  is  improved. 

Other  methods  are  in  use  for  obtaining  blocks  of 
rubber  from  the  crude  and  washed  materials,  which 
consist  in  forcing  it  into  moulds  without  masticat- 
ing, and  consolidating  it  by  placing  the  moulds, 
keyed  or  wedged  together  with  their  charge,  in  a 
heater  at  about  240°  F.  for  a  few  hours.  Washed 
Para  yields  good  sound  blocks  in  this  way,  but  the 
rubber  is  deprived  of  more  of  its  strength  than  if 
masticated,  and  is  darker  in  color. 

The  blocks  are  next  cut  up  into  sheets  of  different 
thicknesses.  Square  blocks  are  clamped  to  a  plate, 
which  can  be^  raised  to  any  height,  according  to  the 
thickness  of  sheet  required.  This  passes  forward  to 
an  oscillating  knife,  which  slices  up  the  rubber. 
The  knife  can,  be  set  in  an  opposite  direction,  so  as. 


TREATMENT  OF  CRUDE  RUBBER.       103 

to  make  another  cut  as  it  passes  back  again,  and  so 
on.  Cylindrical  blocks  are  forced  upon  a  stout 
.spindle,  which  rotates  in  front  of  a  similar,  though 
much  longer  knife.  The  thickness  of  sheet  is  reg- 
ulated by  the  feed-wheels,  which  are  changed  as 
required,  and  when  the  machine  is  once  started,  a 
block  can  be  cut  without  further  attention  unless 
demanded  by  a  defect  in  the  machine  itself,  which 
occurs  generally  in  the  friction  arrangement  which 
works  the  feeding  gear.  The  machines  are  worked 
at  very  high  speeds,  and  a  good  supply  of  water  is 
kept  continually  flowing  over  the  knives.  The 
sheets  are  generally  hung  up  to  dry  and  season,  and 
are  soaped,  and  laid  carefully  one  on  the  other,  or 
rolled  up  for  storage.  The  cutting  up  must  be 
done  in  a  cool  room,  for  if  the  rubber  gets  soft,  it 
must  be  again  placed  in  a  cold  place  to  harden. 
Soft  spots  or  patches  will  lead  to  inequalities  in  the 
thickness. 

The  most  usual  commercial  thicknesses  in  which 
these  plates  are  manufactured  are  measured  accord- 
ing to  the  following  scale  for  the  numbers : 
Nos.     1234567 

4.15  3.26  2.58  2.35  1.85  1.66  1.40  millimeters. 
Nos.     8       9      10      11      12     13     14 

1.14  0.96  0.83  0.62  0.54  0.46  0.41  millimeters. 
Nos.     15      16      17      18 

0.37  0.33  0.20  0.18  millimeters. 
The  manufacture  of  fine  cut  sheet  was  invented 
by  Charles  Macintosh,  and  was  for  a  long  time  pro- 
tected   by    patent,    which    was    owned    by    Charles 


104    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

Macintosh  and  Co.  They  are,  however,  now  manu- 
factured by  several  English  firms  and  also  in 
Fance  and  in  Germany.  They  are  frequently 
colored  brown,  red  or  green  by  the  admixture  of 
pigment,  but  green  sheets  have  now  almost  entirely 
disappeared,  black  and  brown  being  preferred,  as 
they  are  better  in  quality. 

Up  to  within  a  few  years  adulteration  of  fine 
cut  sheet  was  entirely  unknown,  but  at  present 
sheets  are  brought  into  commerce,  which  for  the 
purpose  of  reducing  the  price,  and  frequently  also 
with  the  object  of  defrauding,  contain  up  to  one- 
third  of  cheaper  substitutes. 

In  a  similar  manner  as  fine  cut  sheets,  square 
threads  may  be  cut  from  the  pressed  blocks.  These 
threads  were  formerly  frequently  used  in  this  crudo 
non-vulcanized  state,  but  at  present  they  are  seldom 
employed,  since  non-vulcanized  rubber  becomes 
hard  at  32°  F.,  and  soft  and  sticky  at  over  86°  F. 

If,  on  the  other  hand,  mixed  mass  is  to  be  pre- 
pared from  the  washed  crude  rubber,  the  latter 
must  first  be  softened  by  passing  it  through  the 
heated  macerating  rolls  to  soften  it  for  the  reception 
of  the  admixtures.  Mixing  is,  as  a  rule,  effected  in 
the  same  machine,  which  then  serves  as  macerating 
and  mixing  rolls.  A  Frenchman  has  humorously 
designated  the  manufacture  of  rubber  as  "  the  art 
of  mixing  rubber  with  cheap  substances  without 
impairing  too  much  its  special  properties."  In 
order  to  be  right,  he  might  have  added,  "  and  to 
make  its  application  more  suitable  for  various  pur- 


TREATMENT  OP  CRUDE  RUBBER.       105 

poses  or  to  cheapen  it."  In  fact  in  no  other 
industry  is  there  a  material  which  is  so  receptive  to 
these  manipulations,  and  to  which  it  is  possible  to 
impart  so  many  varying  qualities.  The  admix- 
tures consist  of  sulphur  in  sufficient  quantity  for 
vulcanization,  and  of  other  substances  conditional 
either  on  the  future  use  for  which  the  material  is 
intended  or  for  the  production  of  an  exactly  deter- 
mined degree  of  hardness,  tenacity,  as  well  as  of 
color,  or  finally  for  the  purpose  of  cheapening  the 
product.  The  principal  ingredients  used  are,  lith- 
arge, zinc-white,  chalk,  heavy  spar,  metal,  asbestos, 
ground  hemp  and  a  few  other  substances  such  as 
glass  dust,  fine  sand,  etc.,  which,  however,  are  less 
frequently  employed.  Besides  zinc-white,  already 
mentioned,  the  following  materials  are  used  for 
coloring:  Cinnabar,  antimony  pentasulphide,  ferric 
oxicle,  ochre,  ivory  black  and  lamp  black.  The 
receipts  for  these  mixtures  upon  which  besides 
the  choice  and  use  of  the  right  variety  of  crude 
rubber,  the  production  of  the  innumerable  various 
qualities  of  vulcanized  rubber  depends,  are  jealously 
guarded  in  the  various  factories  as  trade  secrets. 
For  an  exact  repetition  of  a  certain  composition,  an 
actual  knowledge  of  the  ingredients  used  is  abso- 
lutely necessary,  since  a  chemical  analysis  does  not 
furnish  sufficient  guiding  points  for  reasons  which 
will  be  explained  later  on,  and  even  practical 
experiments  give  only  an  approximately  favorable 
result  after  long  futile  groping. 

The  manipulation  of  kneading  and  mixing  is  very 


106    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

simple,  and  is  readily  understood  from  the  construc- 
tion of  the  machine  and  the  nature  of  the  material 
to  be  worked.  The  quantities  of  washed  crude 
rubber,  which,  of  course,  must  not  be  of  the  same 
kind,  but  of  different  varieties,  which  are  required 
for  the  intended  quality  of  the  mass,  and  the  sub- 
stances to  be  added,  are  carefully  weighed  and  then 
introduced  together  in  small  portions  between  the 
rolls.  The  larger  part  of  the  material  combines  at 
once  to  a  plastic  mass,  which  either  adheres  by 
itself  to  the  front  roll  and  is  carried  along  by  it,  or 
if  such  is  not  the  case,  is'taken  up  by  the  hand  of 
the  workman  and  lifted  up.  In  this  manner  a  loose 
mantle  is  rapidly  formed  upon  the  front  roll,  which 
glides  through  between  the  rolls  as  long  as  the 
machine  is  in  operation.  The  material  not  taken 
up  by  the  roll,  or  crumbs  which  become  detached 
and  fall  upon  the  sheet  underneath  the  rolls,  are 
carefully  gathered  up  and  fed  from  above  the  rolls. 
The  mass  having  several  times  passed  through  be- 
tween the  rolls,  the  mantle  is  cut  open  crosswise  with 
a  short  sharp  knife,  made  into  a  roll,  and  the  latter, 
head  foremost,  is  again  passed  through  between  the 
rolls.  This  operation  is  repeated  until  uniform 
maceration  and  mixing  have  been  effected.  The 
mass  in  the  form  of  a  roll  is  then  taken  from  the 
machine  in  the  manner  just  described. 

In  another  form  of  machine,  the  rolls  revolve  in 
an  iron  box,  the  object  of  this  being  to  prevent 
crumbs  from  falling  down,  and  to  save  the  attend- 
ance of  a  workman.  Theoretically,  this  construe- 


TREATMENT    OF    CRUDP:    RUBBER. 


107 


tion  is  correct,  arul  it  will  be  referred  to  later  under 
gutta  percha,  in  the  manipulation  of  which  it  is 
used,  but  in  the  rubber  industry  it  has  been  found 
to  be  of  no  practical  value. 

The  rolls  of  rubber  taken  from  the  mixing  ma- 

FIG.  4. 


chine  are  brought  into  a  calender  to  be  rolled  into 
sheets.  Fig.  4  represents  a  calender  with  four  rolls. 
A,  A!,  A 2,  A 3  are  four  chilled  iron  rolls  cast  hollow, 
so  as  to  admit  steam  or  water.  A  and  A3  (Fig.  4) 
can  be  moved  nearer  to  or  further  from  Ax,  and  A 


108        INDIA    RUBBER,  (IUTTA    PERCHA,  BALATA. 

by  screw-geariug  worked  by  a  wheel  C  and  C2.  The 
temperature  of  the  rolls  exerting  great  influence 
upon  the  uniformity  of  the  sheets  as  well  as  upon 
the  avoidance  of  stripes,  so-called  flowers,  and 
especially  of  air  bubbles,  provision  is  made  for  the 
admission  of  cold  water  by  a  pipe  on  the  axis  of 
each  roll,  and  in  addition  there  is  a  pipe  for  the 
discharge  of  steam  as  well  as  of  water.  The  sheets 
as  they  come  from  the  rolls  are  caught  by  a  cloth, 
and,  to  prevent  sticking  together,  are  rolled  together 
with  it  upon  a  wooden  spindle. 


CHAPTER    III. 

VULCANIZATION. 

BEFORE  describing  this  operation  -,\  brief  reference 

to  some  of  the  characteristic  peculiarities  of  crude 
non-vulcanized  rubber  may  be  of  service.  As  has 
previously  been  mentioned,  at  a  temperature  of  SO0 
F.  it  commences  to  get  soft,  and  at  122°  F.  becomes 
very  adhesive.  But,  on  the  other  hand,  at  a  tem- 
perature of  50°  F.  it  becomes  hard  and  stiff,  and  at 
32°  F.  thin  plates  will  break  after  being  repeatedly 
bent  backward  and  forward.  By  the  action  of 
atmospheric  air  and  light,  and  especially  in  the 
presence  of  moisture  and  heat,  crude  rubber  is  oxid- 
ized and  becomes  a  pitch-like,  sticky  mass.  By  the 
discovery  of  vulcanization  these  evils  have  been 
removed  without  impairing  the  valuable  properties 
of  rubber.  Vulcanization  is  effected  by  combining 
rubber  with  sulphur  with  the  assistance  of  heat. 

The  celebrated  French  chemist  Anselme  Payen 
has  made  very  interesting  experiments  in  this  direc- 
tion, and  ascertained  that  w-hen  a  disk  of  crude 
rubber  is  submerged  in  a  bath  of  melted  sulphur,  it 
swells  up  at  248°  F.,  and  absorbs  a  certain  quantity 
of  sulphur.  In  the  course  of  a  quarter  of  an  hour 
the  rubber  shows  no  essential  change,  it  being 
always  sticky  when  touched.  By  continuing,  how- 
(109) 


110      INDIA  RUBBER,  GUTTA  PRRCHA,  BALATA. 

ever,  the  experiment  30  to  40  minutes  and  raising 
the  temperature- to  206°  to  284°  F.,  the  rubber 
acquires  a  yellowish  color,  it  is  no  longer  sticky,  its 
elasticity  is  considerably  increased,  and  it  is  no 
longer  changed  by  the  influence  of  cold.  The  same 
effect  is  produced  when  rubber  previously  mixed 
with  flowers  of  sulphur  is  exposed  for  the  same 
length  of  time  to  a  temperature  of  266°  to  284°  F., 
and  also  at  every  degree  of  heat  between  the  melting 
point  of  sulphur  and  320°  F.,  the  effect  being  the 
quicker  the  higher  the  temperature  is. 

In  this  experiment  are  included  all  the  distinc- 
tive features  of  the  vulcanizing  process.  However, 
vulcanization  can  be  effected  not  only  by  pure 
sulphur,  but  also  by  means  of  different  sulphides, 
with  chloride  of  sulphur,  and  several  other  sub- 
stances, such  as  iodine,  bromine,  etc.  For  industrial 
purposes,  however,  only  pure  sulphur  is  employed, 
and  for  special  purposes  the  so-called  cold  vulcaniza- 
tion with  carbon  disulphide  and  chloride  of  sulphur. 

Cold  vulcanization.  According  to  this  process, 
which  was  invented  in  1846  by  Parkes,  of  Birming- 
ham, the  rubber  is  suspended  for  a  shorter  or  longer 
time — 1J  to  3  minutes,  according  to  thickness  of 
the  articles — in  a  cold  mixture  of  100  parts  of  car- 
bon disulphide  and  2J  parts  of  dichloride  of  sul- 
phur. When  taken  from  the  bath  the  articles  are 
quickly  dried  in  a  current  of  air  of  77°  F.,  or,  in 
order  to  prevent  the  dichloride  of  sulphur  from 
acting  for  too  long  a  time,  they  are  first  immersed 
in  lukewarm  water  and  then  dried.  In  place  of 


VULCANIZATION.  Ill 

carbon  disulphide,  carefully  refined  petroleum  may 
be  used. 

This  process  of  vulcanizing  is  extensively  used 
for  surface-curing,  such  as  single  textures  for  gar- 
ments and  sundry  small  articles  manufactured  from 
masticated  sheet  rubber,  such  as  tobacco  pouches, 
tubing,  rings,  etc.  For  thinner  articles  it  has  been 
recommended  to  use":  Dichloride  of  sulphur  1  part 
by  weight,  carbon  disulphide  30  to  40  parts,  and  to 
suspend  the  articles  in  the  bath  for  60  to  80  seconds. 

For  thicker  articles  the  following  bath  is  recom- 
mended :  Dichloride  of  sulphur  1  part  by  weight, 
carbon  disulphide  GO  to  80  parts.  Allo\v  the  articles 
to  remain  in  the  bath  for  3,  4,  to  5  minutes. 
Articles  of  extra  thickness  must  be  repeatedly 
plunged  into  the  fluid  until  vulcanization  is  com- 
plete, when  they  are  washed  and  dried. 

It  is,  however,  more  suitable  in  all  cases  to  work 
with  a  reduced  solution  of  dichloride  of  sulphur,  as 
it  is  then  possible  to  stop  vulcanization  at  any 
moment.  If  the  articles  are  allowed  to  remain  too 
long  in  the  solution,  over-vulcanization  may  take 
place,  that  is,  the  surface  .of  the  articles  becomes 
hard  and  brittle. 

Small  articles,  especially  such  as  have  sharp  out- 
lines produced  by  stamping,  can  be  perfectly  vul- 
canized by  this  method  and  their  outlines  preserved, 
which  they  would  lose  by  any  other  process. 
Articles  of  special  beauty  should  be  thoroughly 
washed  when  taken  from  the  bath,  and  then  im- 
mersed for  50  to  70  minutes  in  boiling  caustic  soda 


112        INDIA    RUBBER,  GUTTA    PERCITA,  BALATA. 

solution  of  moderate  strength.  The  caustic  soda 
dissolves  the  free  sulphur  and  the  surface  of  the 
article  will  present  a  uniformly  gray  color. 

It  is  immaterial  whether  solutions  of  dichloride 
of  sulphur  in  carbon  disulphide,  or  solutions  pre- 
pared with  the  aid  of  anhydrous  petroleum  are 
used.  For  the  sake  of  completeness  the  preparation 
of  dichloride  of  sulphur  and  of  anhydrous  petroleum 
will  here  be  given. 

Preparation  of  dichloi'i'dc.  of  .s///y> /////•.  Dichloride 
of  sulphur  is  very  easily  prepared  by  passing  dry 
chlorine  over  dry  powdered  sulphur.  The  sulphur 
should  be  dried  immediately  before  the  operation, 
and  then  placed  in  a  tubulated  retort  provided  with 
a  receiver  thoroughly  cooled.  The  chlorine  passes 
through  a  pipe  fitted  in  the  tubulure.  Perfectly 
dry  chlorine  is  obtained  by  passing  it  through  a 
pipe  filled  with  pumice  stone  saturated  with  sul- 
phuric acid.  For  the  success  of  the  operation  it  is 
absolutely  necessary  that  both  materials  should  be 
perfectly  dry,  since  dichloride  of  sulphur  decom- 
poses on  coming  in  contact  with  water.  The  ac- 
tion of  the  two  bodies  upon  each  other  commences 
as  soon  as  the  retort  containing  the  sulphur  is 
heated.  A  reddish-yellow  fluid,  consisting  of  a  solu- 
tion of  free  sulphur  with  dichloride  of  sulphur  col- 
lects in  the  receiver.  To  free  the  dichloride  from  the 
free  sulphur  the  liquid  is  distilled  until  it  boils  at 
exactly  260°  F.  Distillation  may,  however,  be 
omitted  if  the  presence  of  free  sulphur  does  not 
exert  a  disturbing  influence  upon  the  vulcanizing 
process. 


VULCANIZATION. 


113 


The  apparatus  shown  in  Fig.  5,  is  well  adapted 
for  the  preparation  of  dichloride  of  sulphur.  The 
chlorine  passes  from  the  developing  vessel  through 
the  pipe  a  into  the  glass  cylinder  G.  The  latter  is 
filled  with  glass  balls  moistened  with  sulphuric  acid, 
and  entirely  dry  chlorine  passes  into  the  earthenware 
vessel  V,  which  is  provided  with  an  earthenware 
lid,  D.  The  lid  is  provided  with  a  neck  E,  which 
serves  for  the  introduction  of  the  sulphur.  The 

FIG.  5. 


vessel  V  stands  in  a  sheet-iron  vessel  filled  with 
paraffin  oil  P,  and  is  heated  so  that  the  sulphur  S 
is  heated  slightly  above  its  fusing  point.  The 
vapors  of  dichloride  of  sulphur  escaping  through 
C,  are  condensed  in  the  glass  receiver  K. 

Dichloride  of  sulphur  is  a  mobile,  reddish  yellow 
liquid,  having  a  peculiar,  penetrating,  disagreeable 
odor,  and  fuming  strongly  in  the  air.  Specific 
gravity  =  1.680.  It  boils  at  276.8°  F.  Brought 
in  contact  with  moisture,  it  decomposes,  forming 
8 


114        INDIA    RUBBER,  GTJTTA    PERCHA,  BALATA. 

hydrochloric  and  sulphurous  acids,  and  causing  a 
deposit  of  sulphur  upon  the  neck  of  the  bottle. 

As  dichloride  of  sulphur  severely  attacks  the 
mucous  membranes  of  the  nose  and  mouth,  as  well 
as  the  eyes,  and  produces  a  convulsive  cough  and 
difficulty  of  breathing,  followed,  if  the  air  impreg- 
nated with  its  poisonous  vapors  is  inhaled  for  any 
length  of  time,  by  lung  and  throat  diseases,  the 
greatest  precaution  should  be  observed  to  protect  the 
workmen  from  its  evil  effects.  It  should  be  kept  in 
bottles  with  ground-glass  stoppers. 

Preparation  of  anhydrous  petroleum.  For  this  pur- 
pose bring  the  petroleum  into  a  tank  lined  with  lead 
and  provided  writh  a  stirring  apparatus.  Mix  it 
with  the  tenth  part  of  its  weight  of  sulphuric  acid, 
and  after  stirring  the  mixture  for  several  hours, 
allow  it  to  rest.  The  supernatant  petroleum  is  then 
brought  into  a  still,  and  to  every  100  parts  of  it  add 
J  part  of  burned  lime,  finely  powdered,  to  fix  the 
last  traces  of  acid.  The  petroleum  is  then  distilled 
off.  To  prevent  the  petroleum  thus  rectified  from 
absorbing  moisture  from  the  atmosphere,  it  should 
be  kept  in  glass  bottles  securely  stoppered,  the  bal- 
loons used  for  storing  hydrochloric  acid  being  very 
suitable  for  the  purpose. 

Warm  vulcanization.  According  to  this  method, 
invented  by  Hancock,  the  articles  to  be  vulcanized 
are  brought  into  a  bath  of  melted  sulphur  heated  to 
from  284°  to  302°  F.,  and  allowed  to  remain  in  it 
until  they  are  uniformly  permeated  and  have  ab- 
sorbed about  10  to  15  per  cent,  of  sulphur.  How- 


VULCANIZATION.  115 

ever,  before  the  articles  are  immersed  in  the  bath, 
it  is  advisable  to  spread  them  out  in  a  heated  room 
for  24  to  36  hours,  so  that  the  seams  cemented  to- 
gether with  benzine  or  rubber  solution  may  become 
thoroughly  dry,  as  otherwise  they  may  burst  open. 
After  being  taken  from  the  sulphur  bath,  a  solid 
crust  of  sulphur  is  formed,  on  cooling,  upon  the 
outer  surface  of  the  articles,  which  has  to  be  scraped 
off  or  rubbed  off  upon  grooved  boards.  The  articles 
are  then  placed  in  a  room  heated  to  from  86°  to 
104°  F.  Notwithstanding  the  rubbing  or  scraping 
off  of  the  outer  crust  of  sulphur,  the  articles  vulcan- 
ized according  to  this  method  contain  still  an  excess 
of  sulphur,  which  on  rubbing  or  pulling  the  article, 
deposits  a  fine  gray  powder  on  the  surface.  This 
may  be  readily  remedied  by  washing  in  weak  soda 
solution.  This  method  yields  good  results  with 
articles  made  of  fine  cut  sheets.  When  carefully 
carried  out,  it  is  preferable  to  cold  vulcanization. 

Gerard's  process.  Ge'rard  has  recommended  the 
use  of  concentrated  solution  of  liver  of  sulphur 
(pentasulphide  of  potassium)  for  vulcanizing.  The 
solution  is  obtained  by  fusing  potassium  carbonate 
together  with  sulphur.  By  using  a  smaller  quantity 
of  sulphur,  trisulphide  of  potassium  is  obtained, 
Avith  more  sulphur  than  pentasulphide  of  potassium. 
For  preparing  the  last-named  combination,  the  fol- 
lowing quantities  are  used  : 

Carbonate  of  potassium         .     276.8  parts 
Powdered  sulphur.        .         .     256.0  parts 


116   INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

However,  the  figures  given  above  represent  pure 
carbonate  of  potassium,  i.  e.,  100  per  cent,  potash, 
and  as  the  commercial  article  is  never  entirely 
pure,  a  smaller  quantity  of  sulphur  corresponding 
to  the  percentage  of  potash  in  the  carbonate  must 
be  used. 

The  substances  are  first  reduced  to  a  fine  powder, 
then  quickly  mixed  together,  as  potash  absorbs  con- 
siderable moisture  from  the  atmosphere,  and  fused 
in  a  crucible  in  quantities  of  from  45  to  55  Ibs. 
The  crucible  must  be  comparatively  large,  as  the 
mass,  in  consequence  of  the  escape  of  carbonic  acid, 
strongly  effervesces  during  fusion.  The  mass  is 
kept  at  the  fusing  point  until  effervescence  ceases, 
and  is  then  scooped  with  an  iron  ladle  into  shallow 
sheet-iron  moulds  and  allowed  to  cool.  The  con- 
gealed mass  of  pentasulphide  of  potassium,  com- 
monly called  liver  of  sulphur,  on  account  of  its 
brown  color,  should  at  once  be  brought  into  closely- 
stoppered  glass  vessels,  as  it  decomposes  when  ex- 
posed to  the  air. 

For  vulcanizing,  a  concentrated  solution  (25°  B.) 
of  pentalsulphide  of  potassium  is  used.  The  solu- 
tion is  quickly  brought  to  the  boiling  point  in  a 
porcelain  vessel.  The  articles  are  then  immersed 
in  the  fluid  and  allowed  to  remain  until  vulcaniza- 
tion is  complete. 

This  process  has  the  advantage  of  being  entirely 
innocuous,  and  at  the  same  time  inexpensive.  How- 
ever, to  become  generally  available  it  would  seem  to 
require  further  improvements,  as  experiments  have 


VULCANIZATION.  117 

shown  that  only  thin  pieces  of  rubber  become  thor- 
oughly vulcanized,  thicker  pieces  not  being  uni- 
formly penetrated. 

According  to  another  process  the  rubber  is  al- 
lowed to  remain  for  3  hours  under  a  pressure  of 
three  atmospheres  in  a  solution  of  pentasulphide  of 
calcium  of  25°  B.,  heated  to  284°  F.  When  taken 
from  the  bath  the  rubber  is  washed  in  water  and 
dried.  This  method  yields  excellent  results,  the 
rubber  being  thoroughly  and  uniformly  vulcanized 
and  after  washing  presents  a  smooth,  soft  surface, 
almost  velvety  to  the  touch.  However,  this  method 
is  also  only  suitable  for  articles  of  smaller  dimen- 
sions. For  the  purpose  of  employing  it  for  larger 
articles,  Gerard  recommends  to  mix  the  rubber  with 
finely  powdered  earthy  substances,  calcium  hydrates 
being  most  suitable.  Carefully  mix  in  the  mixing 
rolls  rubber  100  parts,  sulphur  6,  calcium  hydrate 
G  to  10,  and  for  vulcanizing  expose  the  articles, 
according  to  their  thickness,  for  1J  to  3  hours  in  a 
closed  vessel  to  a  steam  or  water  bath  at  284°  F. 

Mechanical  combination  of  rubber  with  sulphur. 
This  process,  invented  by  Goodyear,  is  the  most 
important  and  most  generally  used.  It  consists 
essentially  in  mechanically  mixing  at  the  ordinary 
temperature  a  certain  quantity  of  rubber  with  a 
certain  quantity  of  sulphur,  and  exposing  the  mix- 
ture under  a  certain  pressure  to  a  certain  degree  of 
heat.  To  the  washed  and  dried  rubber  is  added  in 
the  mixing  rolls  7  to  10  per  cent,  flowers  of  sulphur. 
Of  course  for  certain  purposes  the  addition  of  sul- 


118    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

phur  may  vary  between  3  and  15  per  cent.  Care- 
ful and  uniform  mixing  is  absolutely  necessary  for 
the  favorable  progress  of  the  operation,  since  tho 
mass  must  be  thoroughly  homogenous. 

The  work  is  commenced  by  passing  the  rubber 
through  between  the  masticating  rolls  so  as  to  form 
it  into  a  loose  band ;  the  rolls  used  for  this  pur- 
pose should  allow  of  being  heated  by  steam.  The 
spongy  band  thus  obtained  is  again  passed  through 
between  the  rolls,  and  at  the  same  time  is  sprinkled 
with  sulphur.  When  the  requisite  quantity  of  sul- 
phur has  been  applied,  it  is  systematically  kneaded 
in,  which  is  best  accomplished  by  doubling  the 
band  together  and  passing  it  through  between  the 
rolls,  repeating  the  operation  until  a  mass  is  ob- 
tained which  to  the  naked  eye  appears  entirely 
homogeneous.  This  mass,  however,  represents  only 
a  mechanical  compound  of  the  two  substances,  a 
chemical  combination  not  having  been  formed.  It 
is  elastic  in  the  cold,  of  a  brownish  color,  is  but 
slightly  elastic  at  a  higher  temperature,  and  all  the 
sulphur  kneaded  in  can  be  readily  extracted  by 
proper  solvents.  Freshly-cut  surfaces  stick  together, 
and  this  property  is  made  use  of  for  shaping  articles 
from  the  sulphurized  mass  which  are  then  subjected 
to  the  actual  vulcanizing  process.  Articles  may 
also  be  made  from  vulcanized  rubber  by  cementing 
together  the  pieces  composing  them,  but  the  manu- 
facture presents  difficulties. 

Vulcanizing  operation.     As  previously  mentioned, 
the  chemical  combination  between  rubber  and  sul- 


VULCANIZATION.  119 

phur  takes  place  only  when  the  mixture  of  both 
bodies  is  heated  to  a  certain  temperature.  Opinions 
vary  as  to  the  degree  of  heat  required  for  accomplish- 
ing this  chemical  combination,  or  vulcanizing  as  the 
operation  is  called,  the  chief  reason  for  this  differ- 
ence in  opinion  being  due  to  the  fact  that  the  differ- 
ent varieties  of  rubber  do  not  behave  in  the  same 
manner.  All  Asiatic  varieties  (from  the  East  Indies, 
Java,  Borneo),  require  less  time  for  vulcanization 
than  the  finer  qualities  of  American  rubber.  The 
time  required  for  vulcanizing  depends  on  the  thick- 
ness of  the  article,  as  well  as  on  the  quality  and 
origin  of  the  crude  rubber.  Articles  with  smaller 
cross-sections  are  frequently  vulcanized  in  an  hour, 
while  thicker  articles,  and  those  of  larger  dimen- 
sions, require  two  to  three  hours. 

Vulcanization  is  the  most  difficult  and  critical 
operation  in  the  manufacture  of  rubber  goods, 
since  the  consequence  of  a  little  too  much  or  too 
little  may  be  over-vulcanization  or  an  insufficient 
process,  and  these  evils  are  the  more  disagreeable 
since  their  effect,  as  a  rule,  is  only  noticed  when 
the  articles  are  in  actual  use.  No  definite  rules 
can  be  given  in  regard  to  the  proportion  in  which 
sulphur  has  to  be  added,  the  correct  temperature 
and  how  long  each  article  must  remain  in  the 
heater  or  the  press.  This  must  be  left  to  the  in- 
telligence and  experience  of  the  manufacturer.  If 
the  mass  to  be  vulcanized  is  exposed  to  too  high  a 
temperature,  over-vulcanization  or  burning  takes 
place,  whereby  the  rubber  loses  its  elasticity  and 


120    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

soon  becomes  brittle,  especially  upon  the  surfaces. 
If  the  temperature  is  too  low  vulcanization  is  incom- 
plete, and  in  this  case  the  rubber  yields  readily  to 
pressure  or  pull,  without,  however,  rebounding  to  its 
original  condition  when  the  pressure  or  pull  ceases. 

A  temperature  between  248°  and  302°  F.  may 
be  considered  the  limit  in  which  vulcanization  will 
progress  in  a  correct  manner.  In  some  cases  it  may 
be  permissible  to  go  above  this  limit  and  raise  the 
temperature  to  338°  F.,  but  only  for  a  very  short 
time. 

Experiments  have  shown  that  for  properly  vul- 
canizing rubber  it  is  necessary  to  heat  it  above  the 
melting  point  of  sulphur.  Now,  as  sulphur  fuses  at 
235.4°  F.,  theoretically  it  would  suffice  to  heat  the 
mass  to  be  vulcanized  to  somewhat  above  that  tem- 
perature. While  it  is  possible  to  vulcanize  rubber 
at  239°  F.,  this  fact  is  of  little  or  no  value  for  prac- 
tical purposes,  as  at  that  temperature  the  operation 
requires  more  time  than  the  manufacturer  can  afford. 

From  what  has  been  said,  it  will  be  seen  that  the 
temperature  for  vulcanizing  depends  chiefly  on  the 
conditions  under  which  the  manufacturer  works.  If 
he  works  American  rubber,  and  has  to  vulcanize 
articles  with  thick  walls,  a  higher  temperature  is 
required  than  for  East  Indian  material,  and  articles 
with  thin  sides.  It  is,  therefore,  advisable  not  only 
to  work  one  and  the  same  variety  of  rubber  at  one 
time,  but  also  to  subject  only  articles  varying  but 
slightly  in  thickness  to  the  vulcanizing  process  at 
one  time. 


VULCANIZATION.  121 

t 

Vulcanizing  apparatus.  (Generally  speaking,  brick 
chambers  heated  by  hot  air  are  now  antiquated,  and 
are  only  used  here  and  there  in  special  cases,  for 
instance,  in  the  manufacture  of  lacquered  rubber 
shoes  and  a  certain  kind  of  water-proof  stuff.  The 
chambers  are  provided  with  air-tight  doors,  and  the 
floor  consists  of  closely-joined  iron  plates.  Several 
of  such  chambers  adjoin  one  another,  and  are 
heated  by  one  fire.  The  flues  are  arranged  in  such 
a  manner  that  the  tire  gases  must  frequently  pass 
to  and  fro  under  the  iron  plates  of  the  bottoms  of 
the  chambers  and  heat  the  air  in  them  uniformly. 

The  articles  to  be  vulcanized  are  placed  upon 
frames  close  to  the  ceilings  of  the  chambers,  and  the 
fire  is  so  regulated  that  the  thermometers,  which  are 
placed  behind  glass  plates  fitted  into  the  doors  of  the 
chambers,  show  as  uniform  a  temperature  as  pos- 
sible— 266°  to  284°  F.  It  may  be  mentioned  here 
that  with  the  use  of  this  method,  complete  vulcani- 
zation is  frequently  effected  only  by  adding  to  the 
articles  to  be  vulcanized  a  certain  quantity  of 
litharge. 

The  use  of  iron  boilers  with  double  walls  between 
which  steam  is  introduced  to  heat  the  interior  space 
is  based  upon  the  same  principle  as  brick  chambers. 

Vulcanizing  heaters  and  presses,  with  direct  intro- 
duction of  steam,  are  now  in  general  use. 

The  ordinary  steam  heater  is  similar  to  a  steam 
boiler.  The  size  of  the  heaters  varies  according  to 
the  condition  and  dimensions  of  the  articles  to  be 
vulcanized,  Their  diameter  varies  from  3  feet  3 


122    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 


inches  to  20  feet,  and  their  length  from  6^  to  10 
feet,  and  up  to  100  feet  and  more.  The  longest 
heaters  are  used  for  vulcanizing  hose,  because  the 
latter  must,  as  a  rule,  be  vulcanized  full  length 


FIG.  6. 


FIG.  7. 


upon  the  metal  cores  upon  which  they  have 
been  made.  In  England  the  standard  length  of 
hose  is  60  feet,  in  France  82 
feet,  and  in  Germany  98  feet 
and  5  inches  and  even  114  feet 
and  9  inches.  These  dimen- 
sions indicate  the  length  re- 
quired for  the  hose  heater. 
?  Fig.  6  shows  a  heater  in  lon- 
gitudinal section  and  Fig.  7  in 
cross  section.  The  heater  «  <> 
is  16  to  20  feet  long  and  has  a 
diameter  of  4J  to  6 J  feet,  and  is 
constructed  like  an  ordinary  steam  boiler.  In  front 
it  is  provided  with  a  strong  cast  iron  ring  v  v  into 
which  fits  a  similar  ring  u  u  of  the  cover.  To  make 


VULCANIZATION.  123 

a  perfectly  tight  joint  a  tarred  hemp  rope  is  laid  in 
the  groove  of  the  ring  and  the  lid  is  then  tightened 
by  means  of  screws.  The  lid  is  suspended  to  a 
small  crane  T,  'so  that  after  opening  the  heater  it 
can  be  turned  to  the  side,  and  also  be  readily  re- 
placed. For  the  convenient  introduction  and  re- 
"moval  of  the  articles  the  heater  is  furnished  with 
two  iron  rails  upon  which  run  small  carriages 
containing  the  articles  to  be  vulcanized,  and  besides 
suitable  frames  for  the  reception  of  the  articles  may 
also  be  placed  upon  them.  U  is  a  steam  pipe  pro- 
vided with  the  cock  V  for  the  introduction  of 
steam.  The  steam  is  uniformly  distributed  by  pass- 
ing into  a  long  pipe  V,  and  from  the  latter  through 
a  number  of  small  holes  into  the  heater.  X,  is  the 
safety-valve,  I7,  the  cock  for  the  discharge  of  the 
atmospheric  air  and  condensed  water.  In  the 
illustration  are  shown  at  Q  Q  a  few  iron  cylin- 
ders filled  with  buffer  rings,  and  at  R  R  frames 
which  serve  for  holding  rubber  sheets  between  iron 
plates. 

Sheets,  belting,  large  valves,  etc.,  are  vulcanized 
in  a  press,  such  as  shown  in  Fig.  8.  It  consists  of 
two  plates,  the  bottom  plate  c,  which  is  stationary, 
and  the  upper  plate  d,  which  is  movable.  Both 
plates  can  be  heated  by  steam,  and  their  heating 
spaces  are  connected  by  the  spiral  spring  d.  Steam 
is  introduced  from  a  point  on  the  side  of  the  press 
not  shown  in  the  illustration.  The  plate  d  can  be 
raised  sufficiently  by  means  of  the  screws  e,  and 
nuts,  which  are  uniformly  moved  by  a  horizontal 


124    INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 
FIG.  8. 


shaft  by  means  of  the  pulley  pt  to  allow  of  the  sup- 
port which  bears  the  sheet  or  belt  to  be  vulcanized, 
and  glides  upon  the  table  a,  being  brought  between 
c  and  d. 

FIG. 


A  press  heated  by  petroleum  is  shown  in  Fig.  9. 


VULCANIZATION.  125 

It  is  intended  for  smaller  articles,  such  as  rubber 
stamps,  etc. 

Vulcanizing  operation.  Besides  observing  the  right 
temperature  during  heating,  the  mechanical  treat- 
ment of  the  articles  is  also  of  great  importance.  It 
is  not  practicable  simply  to  place  the  articles  to  be 
vulcanized  in  the  heater,  since  in  the  high  tempera- 
ture to  which  they  must  be  exposed  they  would  soften 
to  such  an  extent  as  to  lose  their  shape.  Hence  most 
articles  are  brought  into  the  heater  or  press  in  iron 
moulds,  such  being  the  case  with  pump  valves,  buf- 
fers, thick  rings,  bands,  cushions  for  billiard  tables, 
belts,  door-mats,  balloons,  and  many  other  articles. 
Hose,  as  a  rule,  is  vulcanized  upon  metal  cores,  and 
the  outside  is  firmly  wrapped  with  strips  of  linen. 
The  latter  are  later  on  removed,  and  to  this  is  due 
the  tissue-like  design  frequently  seen  upon  hose  and 
sheets.  If  entirely  smooth  surfaces  are  desired,  paper 
is  occasionally  used. 

For  many  kinds  of  goods  it  is  important  that  the 
metals  forming  the  moulds  should  not  be  readily 
acted  on  by  sulphur  during  the  heating,  as  a  por- 
tion of  the  sulphur  would  be  abstracted  and  leave 
a  stain  of  the  metallic  sulphide  on  the  goods.  Con- 
sequently sheets  of  packing  vulcanized  in  the  press 
are  prevented  from  coming  in  contact  with  the 
metal  by  sheets  of  cloth  or  paper.  Tin  is  the  most 
convenient  metal  for  resisting  the  action  of  sulphur. 
Zinc  sulphide  being  white,  indicates  the  suitability 
of  zinc  for  coating  moulds,  etc.  All  new  zinc  sur- 
faces should  be  well  cleaned  before  use.  A  good 


126    INDIA  RUBBER,  GUTTA  PP:RCHA,  BALATA. 

plan  is  to  dust  them  over  with  sulphur  and  talc, 
and  heat  them  in  the  heater  several  times,  or  they 
give  rise  to  very  troublesome  blistering.  Boiling 
with  caustic  soda  helps  to  prevent  this,  but  it  is  not 
certain  in  its  action.  Brass  moulds  should  be  well 
tinned.  Hard  rubber  or  ebonite  forms  very  con- 
venient moulds,  well  adapted  where  metallic  sur- 
faces would  be  objectionable  from  staining,  etc. 
Stains  from  tin  moulds  or  tinned  surfaces  are  re- 
moved by  leaving  the  vulcanized  articles  in  hydro- 
chloric acid  for  some  time. 

To  prevent  the  articles  from  sticking  to  the 
moulds,  they  are  dusted  over  with  talc  powder. 
The  talc  powder  is  put  in  a  linen  bag,  and  the 
moulds  as  well  as  the  articles  dusted  over  with  it. 
Small  curved  articles  may  be  placed  in  tin  boxes 
filled  with  talc  powder,  and  thus  subjected  to 
heating. 

Thick  sheets  are  prevented  from  warping  during 
heating  by  placing  them  between  iron  p^tes.  Thin 
sheets  are  dusted  over  with  talc  powder,  and  covered 
with  a  linen  cloth.  In  this  condition  they  are 
wound  upon  a  drum  and  brought  into  tho  heater. 
Pressed  hose  and  cords  are  placed  in  closed  or  open 
boxes  in  talc  and  then  vulcanized. 

To  avoid  loss  of  time,  the  articles  to  be  vulcan- 
ized should  be  sorted  before  heating.  The  thin  and 
thick  should  be  treated  separately,  as  the  latter  re- 
quire more  time  for  vulcanizing  than  the  former. 

Many  manufacturers  effect  vulcanizing  in  two 
operations.  In  the  first  operation,  the  heater  is  for 


VULCANIZATION.  127 

a  short  lime  heated  only  to  a  temperature  not  ex- 
ceeding 284°  F.  Articles  that  were  too  soft  to  be 
taken  from  the  moulds  acquire  by  this  operation 
sufficient  solidity  to  be  heated  by  themselves.  It  is 
evident  that  this  plan  is  attended  with  a  loss  of 
time  and  heat,  and  that  it  is  more  advantageous  to 
finish  the  work  in  one  operation. 

For  many  articles  where  it  is  of  special  import- 
ance that  the  mass  of  which  they  are  composed 
should  consist  of  thoroughly  and  uniformly  sulphur- 
i/.ed  rubber,  the  operation  of  vulcanizing  is  some- 
what modified.  The  articles  are  shaped  in  the 
usual  manner  from  pure  rubber,  heated  so  far  as  to 
deprive  it  of  its  elasticity,  and -pressed  in  moulds. 
They  are  then  coated  with  a  saturated  solution  of 
sulphur  in  carbon  disulphide,  and,  while  still  moist, 
dusted  over  with  powdered  sulphur,  care  being  had 
that  the  coating  of  sulphur  is  uniformly  spread  over 
the  entire  surface. 

For  articles  requiring  only  light  treatment,  the 
following  process  is  sufficient :  After  being  made 
from  pure  rubber,  immerse  the  articles  in  oil  of 
turpentine,  and  allow  them  to  remain  until  their 
surfaces  have  become  somewhat  sticky.  Then  dust 
them  over  with  finely-powdered  sulphur,  avoiding 
an  excess  of  it. 

The  articles  treated  with  saturated  solution  of 
sulphur  in  carbon  disulphide,  or  simply  dusted  over 
with  powdered  sulphur,  are  vulcanized  in  the  same 
manner  as  articles  of  sulphurized  rubber.  Thin 
articles,  when  prepared  with  sufficient  care,  become 


128    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

in  this  manner  thoroughly  vulcanized,  but  thicker 
articles  do  not,  the  product  not  being  uniform.  A 
cross-section  will  show  plainly  that  only  the  surface 
is  vulcanized,  the  interior  parts  remaining  unaltered. 

In  the  manufacture  of  the  various  red  colored 
rubber  articles,  hose,  combs,  etc.,  vulcanization  is 
effected  by  an  addition  of  pcntasulphide  of  anti- 
mony. The  preparations  of  pentasulphide  of  anti- 
mony for  this  purpose  found  in  commerce  differ, 
however,  very  much  in  their  action  in  so  far  that  in 
vulcanizing,  one  kind  gives  always  the  desired  red 
coloration,  while  another,  which  is  not  appreciably 
distinguished  from  it  by  color  or  content  of  sulphur, 
frequently  or  always  yields  a  faulty  product  which 
shows  itself  by  the  color  turning,  or  stains  upon  the 
surface.  The  cause  of  this  difference  in  behavior  of 
the  pentasulphide  of  antimony  is  not  yet  known. 

Turner  fuses  bismuth  5  pounds  and  lead  5 
pounds,  mixes  them,  compounds  the  mixture  with 
half  its  weight  of  sulphur,  pulverizes  after  cooling, 
and  mixes  10  pounds  of  the  compound  with  30 
pounds  of  rubber.  The  articles  vulcanized  with 
this  mixture  are  said  to  stand  a  temperature  of 
392°  F. 


CHAPTER  IV. 

RUBBER    COMPOUNDS. 

FOR  the  manufacture  of  articles  which  are  to 
possess  in  a  very  high  degree  the  property  of  elas- 
ticity combined  with  toughness  the  use  of  pure  sul- 
phurized rubber,  /.  e.,  a  mass  which  lias  been  pre- 
pared from  pure  rubber  and  sulphur  according  to 
one  of  the  methods  described,  is  absolutely  neces- 
sary. In  some  cases,  however,  elasticity  is  not  so 
much  required  as  cheapness  of  production,  for 
instance  toys  for  children,  little  cups,  saucers,  tubs, 
etc.  Such  articles  contain  a  very  small  proportion 
of  rubber,  but  many  admixtures. 

The  substances  used  as  admixtures  depend  on  the 
properties  the  articles  are  to  possess.  If  a  light 
color  and  little  weight  is  desired,  either  fine  white 
pipe-clay,  chalk,  or  magnesia  is  mixed  with  the 
mass  to  be  vulcanized.  For  white  masses  of  greater 
weight,  oxide  of  zinc  is  used,  or  sulphate  of  lead 
which,  being  a  waste  product  of  chemical  factories, 
can  be  procured  at  a  comparatively  small  cost. 

Cinnabar,  round  lake,  sesqui-oxide  of  iron  (caput 

mortunm,  colcothar)  are  generally  added  to  produce 

a  red  color ;  ultra-marine  or  smalt  may  be  used  for 

blue ;  chrome  yellow  furnishes  the  yellow  color ;  a 

9  ( 129  ) 


130    INDIA  RUBBER,  GUTTA  PERCHA, BALATA. 

mixture  of  chrome  yellow  and  ultra-marine,  green  ; 
colcothar  and  ultra-marine,  violet,  etc. 

Uniform  coloring  can  only  be  effected  by  care- 
fully kneading  the  coloring  matter  into  the  rubber 
compound.  But  it  can  also  be  uniformly  colored 
by  producing  certain  chemical  combinations  in  the 
mass  itself,  and  some  receipts  for  that  purpose, 
applicable  to  rubber  as  well  as  gutta  percha,  are 
here  given. 

For  black  a  fluid  is  used  consisting  of: 

Blue  vitriol        .         .         .         .         1  Ib. 

Water 11  Ibs. 

Caustic  ammonia       .         .         .         1  Ib. 
Muriate  of  ammonia          .         .         J  Ib. 

The  blue  vitriol  is  dissolved  in  water  together 
with  the  muriate  of  ammonia,  and  the  caustic 
ammonia  is  then  added. 

For  green  the  following  are  used  : 

Blue  vitriol       .         .         .         .         \  Ib. 
Muriate  of  ammonia           .         .         1  Ib. 
Burned  lime      .         .         .         .2  Ibs. 
Water 11  Ibs. 

For  violet : 

Blue  vitriol        .         .  .  .  J  Ib. 

Sulphate  of  potassium  .  .  1  Ib. 

Phenicine          .         .  .  .  J  Ib. 

Water  11  Ibs. 


RUBBER    COMPOUNDS.  131 

The  articles  to  be  dyed  are  boiled  in  their  respec- 
tive fluids  from  15  to  30  minutes,  but  articles  some- 
what thicker  must  be  boiled  for  a  longer  time  to 
make  the  coloring  uniform.  The  dyed  articles  can 
then  be  vulcanized  in  the  usual  manner. 

Rubber  compounds  which  require  to  be  rough 
are  mixed  either  with  powdered  pumice-stone  or 
the  finest  drift  sand.  The  Jast  two  are  added  to 
the  mass  at  the  time  when  the  sulphur  is  kneaded 
in,  or  in  case  the  process  of  vulcanizing  with  a  fluid 
— chloride  of  sulphur — is  used,  they  are  added  to  the 
pure  rubber.  To  insure  a  completely  uniform  com- 
bination of  the  added  ingredients,  as  clay,  magnesia, 
pumice-stone,  etc.,  it  is  absolutely  necessary  that 
they  should  be  powdered  as  fine  as  possible,  care- 
fully washed,  and  then  thoroughly  dried,  as  the 
presence  of  moisture  is  very  detrimental. 

White  or  black  pitch  is  also  added  to  the  rubber 
mass  for  the  purpose  of  manufacturing  cheap  pro- 
ducts ;  although  many  manufacturers  assert  that 
the  properties  of  the  product  are  essentially  im- 
proved by  such  additions.  This  assertion,  however, 
is  not  true,  and  is  probably  only  made  for  the  pur- 
pose of  hiding  the  real  object  of  these  admixtures, 
namely,  the  production  of  masses  in  a  cheap  man- 
ner. In  the  following  some  receipts  are  given  for 
preparing  rubber  compounds.  These  receipts  have 
been  tried  and  found  useful. 


132    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

White  rubber  masses. 

Parts  by  weight. 

Rubber 100 

Sulphur 10  to  20 

Chalk 40  to  GO 

Magnesia  .         .         .  5  to  40 

Oxide  of  zinc    .         .         .         .  20  to  30 

If  the  composition  is  to  be  colored,  the  coloring 
agent  takes  the  place  of  one  of  the  other  com- 
ponents, either  of  chalk,  magnesia,  or  oxide  of  zinc. 
This  compound  stands  vulcanizing  at  a  high  tem- 
perature and  can  be  finished  in  one  operation. 

Cheap  Rubber  masses  with  an  addition  of  Resin. 

Parts  by  weight. 


Rubber  .     100  200  200 

Sulphur         .  .  25  25  50 

White  pitch,  or  .  15  18  25 

Pine  resin      .  .  12  6C  20 

Masses  prepared  with  an  addition  of  pitch  or 
resin  cannot  stand  a  high  vulcanizing  temperature. 
When  heated  from  284°  to  302°  F.  they  become  so 
soft  that  the  mass  would  collapse  over  the  mould. 
Therefore  in  vulcanizing  it  should  only  be  heated 
very  little  above  the  melting  point  of  sulphur, 
235.4°  F.  A  temperature  between  239°  and  248° 
F.  will  be  most  suitable  for  the  purpose.  Thinner 
articles  prepared  from  these  masses  are  quite  elastic, 
but  thicker  ones  are  less  so. 


RUBBER    COMPOUNDS.  133 

The  Franco- American  Rubber  Co.  prepares 
metallized  rubber  by  mixing  rubber  with  pulverized 
metallic  lead,  zinc,  or  antimony,  and  vulcanizing 
in  the  usual  manner. 

For  the  preparation  of  vulcanized  rubber  which 
does  not  swell  up  when  brought  in  contact  w7ith  fat, 
Schwanitz,  according  to  a  patent  granted  to  him  in 
Germany,  uses  Para  rubber  6  Ibs.,  whiting  6  Ibs., 
glycerine  of  1.23  specific  gravity  1  lb.,  litharge  3J 
ozs.,  and  flowers  of  sulphur  7  ozs.  The  mass  is 
worked  between  heated  rolls  and  exposed  in  a  gly- 
cerine bath  to  the  action  of  steam  of  a  tension  of 
2  or  more  atmospheres. 

To  make  rubber  pervious  to  perspiration  in  the 
use  for  articles  of  clothing,  Scharff  mixes  it  before 
vulcanizing  with  10  per  cent,  of  wood  cellulose,  the 
sulphur  being  added  at  the  same  time. 

Gerner  mixes  rubber  and  gutta-percha  with  cam- 
phor, cowrie  copal,  mustard  or  hemp  seed,  freed  from 
oil  and  ground. 

For  the  manufacture  of  hard  rubber  articles  the 
camphor  and  copal  are  separately  ground  in  rolls. 
Then  as  much  flowers  of  sulphur  as  is  required  for 
the  articles  to  be  manufactured  is  added,  for  instance, 
1  lb.  of  sulphur,  with  J  lb.  of  camphor  and  f  lb.  of 
copal.  Before  adding  the  rubber  the  mixture  is 
finely  ground  and  forced  through  a  fine  sieve.  In 
working  the  materials  are  moistened  with  naphtha, 
gasoline  or  benzine.  The  quantities  of  camphor  and 
copal  to  be  used  in  the  various  mixtures  for  hard 
and  soft  rubber  products  depend  on  the  kind  and 


134    INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

qualities  of  the  .articles  as  well  as  on  the  purpose 
for  which  they  are  to  be  used.  For  special  kinds 
of  hard  rubber  are  preferably  used  J  Ib.  of  the  cam- 
phor and  copal  mixture,  while  for  other  kinds  J  or 
J  of  this  quantity  suffices.  For  soft  rubber  mixtures 
the  composition  and  treatment  of  the  mixture  are 
the  same  except  that  less  sulphur  is  required. 

In  vulcanizing,  the  temperature  has  to  be  gradu- 
ally raised  with  great  care.  The  mass,  however, 
requires  heating  a  shorter  time  than  ordinary  hard 
rubber,  four  to  five  hours  being  sufficient  according 
to  the  thickness  of  the  articles.  During  the  last  two 
hours  the  temperature  is  to  be  raised  to  313°  to 
320°  F.  In  vulcanizing  soft  rubber  it  is  best  to 
heat  for  the  same  length  of  time  as  in  the  ordinary 
process.  The  temperature  should  be  raised  at  least 
to  280°  F.,  and  in  many  cases  to  313°  to  320°  F. 
The  larger  the  content  of  camphor  and  copal,  the 
higher  must  be  the  temperature. 

Kamptulicon.  The  composition  known  by  this 
name  is  especially  well  adapted  for  the  manufacture 
of  floor  cloths  subjected  to  hard  usage,  for  coating 
articles,  etc.  Genuine  kamptulicon  consists  of  an 
intimate  mixture  of  rubber  and  powdered  cork,  and 
is  prepared  as  follows  : 

Waste  of  cork,  and  old  corks  also,  are  cleansed  by 
washing  several  times  in  water.  The  washed  and 
well-dried  mass  is  comminuted  by  grating  upon  a 
drum  provided  with  small  teeth  like  a  rasp,  and 
then  ground  into  a  fine  powder. 

The  rubber  is  cleansed  in  the  usual  manner,  and 


RUBBER    COMPOUNDS.  135 

rolled  into  thin  bands  between  closely-set  rolls.  The 
bands  are  strewed  uniformly  with  the  powdered 
cork,  and  then  subjected  to  further  treatment.  This 
is  done  in  the  same  manner  as  described  for  prepar- 
ing sulphurized  rubber,  that  is,  by  rolling,  kneading, 
and  repeated  rolling  until  an  entirely  homogeneous 
mixture  has  been  formed.  Finally,  sheets  0.0787  to 
0.1968  inches  thick  are  formed,  and  these  are  covered 
either  on  one  or  both  sides  with  a  coat  of  good  lin- 
seed-oil varnish  or  oil  paint.  Of  course,  with  the 
assistance  of  oil  paint,  sheets  with  various  patterns 
(carpet  and  parquet  designs)  can  be  produced. 

Powdered  sulphur  may  also  be  incorporated  with 
the  rubber  besides  powdered  cork,  and  the  articles 
may  be  subjected  to  heating  after  they  have  been 
formed,  and  in  this  manner  a  vulcanized  kamptuli- 
con  is  obtained. 

The  principal  advantages  of  kamptulicon  are  that 
with  very  little  weight  it  combines  great  elasticity, 
and,  for  this  reason,  is  well  adapted  for  floor  cover- 
ing in  passage-ways,  where  the  noise  made  by  walk- 
ing is  to  be  prevented  as  much  as  possible. 

Kamptulicon  can  be  used  as  a  block  cushion  under 
stamping  presses  to  weaken  the  shock,  but  it  should 
be  inclosed  in  an  iron  ring  to  prevent  splitting.  It 
serves  also  to  make  wheels  for  polishing  brass,  steel, 
German  silver,  and  other  metals.  This  is  done  by 
covering  a  wooden  disk  with  a  piece  of  kamptulicon 
of  the  proper  size. 

A  uniform  color  can  be  made  to  permeate  the 
entire  mass,  which  can  be  worked  into  a  kind  of 


136    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

mosaic  in  floor  coverings.  This  condition  is  ob- 
tained by  incorporating  the  coloring  matter  with 
the  rubber.  Colcothar,  ultra-marine,  lamp-black, 
etc.,  etc.,  are  used  for  this  purpose.  The  masses  col- 
ored by  any  of  the  above  substances  are  rolled  out, 
and  it  is  then  a  very  easy  matter  to  cut  stars  or 
other  designs  from  them  by  means  of  a  sharp  knife 
or  a  suitable  die,  and  to  combine  these  into  any 
desired  pattern.  As  the  matter  is  colored  through 
and  through,  floor-cloths,  or  other  articles  manu- 
factured in  this  manner,  retain  their  beauty  as  long 
as  the  articles  themselves  last. 

Rubber  leather.  Generally  speaking  this  is  identi- 
cal with  kamptulicon,  although  it  is  sometimes 
manufactured  in  a  different  manner.  While  genu- 
ine kamptulicon  is  always  composed  of  rubber  and 
cork,  rubber  leather  frequently  contains,  instead  of 
cork,  any  kind  of  fibrous  substance,  such  as  hemp, 
flax,  jute,  etc.  It  is  generally  manufactured  as 
follows:  Rubber  mostly  in  the  form  of  small  waste 
pieces,  of  which  there  will  always  be  large  quanti- 
ties in  rubber  factories,  is  either  entirely  dissolved 
by  a  solvent  or  at  least  allowed  to  swell  up  very 
much.  The  fibrous  substance  is  then  incorporated 
with  the  mass,  and  the  latter  is  made  homogeneous 
by  long-continued  rolling. 

The  easiest  way  of  incorporating  the  fibrous  sub- 
stance is  by  stirring  as  much  of  it  into  the  half-fluid 
mass  of  rubber  and  solvent — refined  petroleum  being 
the  best  for  this  purpose — as  can  conveniently  be 
done.  The  mass  is  then  placed  upon  a  table,  which 


RUBBER    COMPOUNDS.  137 

is  quite  thickly  strewn  with  fibrous  substance,  and 
rolled  into  a  cylinder.  When  in  this  manner  a 
mass  has  finally  been  obtained,  which  possesses 
sufficient  consistency  to  allow  of  it  being  worked 
between  the  rolls,  the  incorporation  of  fibrous  sub- 
stance is  continued  there  until  a  sufficient  quantity 
of  it  has  been  kneaded  -in  to  impart  a  suitable 
degree  of  solidity  to  the  mass. 

It  is  advisable  to  repeatedly  form  the  bands, 
which  have  been  obtained  by  rolling,  into  lumps, 
and  to  pass  these  again  through  the  rolls,  as  by 
these  means  the  fibres  are  piled  in  different  direc- 
tions (forming,  so  to  say,  a  kind  of  felt),  and  by 
doing  this  the  solidity  of  the  substance  will  be  con- 
siderably increased. 

As  far  as  solidity  and  tenacity  are  concerned, 
rubber  leather  surpasses  by  far  kamptulicon  ;  but 
the  latter  is  softer  and  more  elastic.  Kamptulicon 
being  rather  expensive,  it  has  been  largely  super- 
seded by  linoleum,  which  is  manufactured  from  a 
mixture  of  cork-meal,  linseed  oil  and  small  addi- 
tions of  resins. 

Ealenite  or  artificial  whalebone  is  a  material,  as  in- 
dicated by  the  name,  intended  to  serve  as  a  substitute 
for  genuine  whalebone.  A  mass  to  answer  the  in- 
tended purpose  must  possess  considerable  elasticity 
as  well  as  solidity — must,  therefore,  be  a  medium 
between  soft  and  hard  rubber.  A  mass  answering 
the  purpose  very  well  is  prepared  according  to  the 
following  formula : 


138    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

Parts  by  Weight, 

Rubber 100 

Ruby  shellac         ....  20 

Calcined  magnesia        ...  20 

Sulphur        .         .  .         .  25 

Pentasulpide  of  antimony     .         .  20 

The  foreign  substances  are  incorporated  with  the 
rubber,  the  mass  is  pressed  into  moulds,  generally 
plates  or  prismatic  bars,  and  vulcanized  at  a  moder- 
ate heat.  The  mass  which  is  thus  obtained  may  serve 
in  all  cases  as  a  substitute  for  the  genuine  whalebone, 
and  may  also  be  used  for  bobbins,  etc.  On  account 
of  its  light  weight  and  indestructibility,  balenite 
may  be  highly  recommended  for  the  manufacture 
of  gunstocks,  as  also  of  elastic  plates  and  splints  for 
surgical  purposes. 

Plastite.  This  substance  resembles  bard  rubber, 
but  differing  from  it  in  being  non-elastic,  although 
quite  hard.  As  it  can  be  brought  into  any  shape 
desired,  and  is  largely  composed  of  inexpensive 
substances,  it  is  especially  adapted  for  the  manu- 
facture of  pressed  ornaments,  small  frames,  boxes, 
heels  of  shoes,  etc.;  in  short,  for  all  purposes  for 
which  wool,  metal,  horn,  etc.,  are  used. 

Coal-tar  asphaltum  is  an  important  component 
of  plastite.  It  forms  .a  deep  black,  shiny  and  hard 
mass,  and  is  gained  in  the  distillation  of  coal-tar,  as 
residuum  after  all  volatile  substances  have  been 
distilled  off.  Besides  coal-tar,  asphaltum,  sulphur, 
and  magnesia,  and  sometimes  pentasulphide  of 
antimony  form  a  part  of  plastite. 


RUBBER    COMPOUNDS.  139 

Magnesia  can  be  very  well  replaced  by  other  in- 
different substances,  such  as  finely  powdered  and 
washed  chalk,  etc.,  but  the  use  of  magnesia,  which 
is  a  very  light  substance,  offers  the  advantage  that 
the  masses  can  be  made  of  great  volume,  and  at  the 
same  time  of  little  weight. 

A  plastite  mass  possessing  very  good  properties 
may  be  prepared  according  to  the  following  formula  : 

Parts  by  Weight. 

Rubber          ....  100 

Sulphur  .  .  .  .  20  to  25 
Magnesia  .  .  .  .  40  to  50 
Pentasulphide  of  antimony  .  40  to  50 
Coal-tar  asphaltum  .  .  50  to  60 

The  foreign  substances  are  incorporated  with  the 
rubber  in  the  usual  manner.  The  separate  articles 
are  pressed  in  hot  iron  moulds,  and  are  then  heated. 
On  account  of  its  great  hardness  and  solidity,  plastite 
takes  a  high  degree  of  smoothness  and  polish,  and 
for  this  reason  is  well  adapted  for  the  manufacture 
of  handles  for  umbrellas  and  canes,  door-knobs,  etc. 

GRINDING  AND  POLISHING  COMPOSITIONS. — Rub- 
ber possesses  the  specific  property  of  holding  foreign 
substances,  once  incorporated  with  it,  very  tena- 
ciously. If  the  incorporated  substances  are  hard, 
the  mass  is  suitable  for  grinding  or  sharpening ;  if 
soft,  the  composition  serves  for  polishing.  The 
first  category  includes  powdered  pumice-stone, 
powdered  glass,  quartz,  sand,  emery.  To  the 
second  class  belong  colcothar,  graphite,  talc. 


140   INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 


Below  several  formulse   are  given,   which   have 
been  highly  recommended,  especially  for  sharpen 
ing  and  polishing  knives  : 


I. 


Rubber 

Powdered  emery 
Lampblack 


Rubber 

Graphite 

Lampblack 


Rubber 

Graphite 

Lampblack 


Rubber 
Zinc-white  . 
Yellow  ochre 


Rubber 
Sulphur 
Powdered  emery  . 


II. 


III. 


IV, 


V. 


Parts  by  weight. 

.       280 
.     1120 


Parts  by  weight. 

.       280 
.       512 


Parts  by  weight. 

.       280 
.       488 


Parts  by  weight. 
.       280 
84 
1120 


Parts  by  weight. 
.       280 
84 
1120 


RUBBER    COMPOUNDS.  141 

As  will  be  seen,  formula  I.  and  V.  contain  emery, 
which,  on  account  of  its  hardness,  serves  as  a  grind- 
ing agent.  The  addition  of  lampblack  in  the  other 
compositions  is  not  essential,  as  the  only  object  of 
it  is  to  give  them  a  black  color.  Nos.  II.  and  III., 
on  account  of  the  percentage  of  graphite  they  con- 
tain, must  be  considered  as  polishing  compositions ; 
and  No.  IV.  also  possesses  the  same  property. 

It  has  been  endeavored  to  prepare  compositions 
which  shall  answer  for  one  or  the  other  purpose ; 
but  one  suitable  for  grinding,  and  at  the  same  time 
for  polishing,  can  only  be  prepared  by  using  a 
hard  body  in  the  form  of  an  impalpable  powder, 
equaling  in  fineness  the  very  finest  flour. 

Graphite  and  talc,  which  of  course  must  be  pow- 
dered as  finely  as  possible  and  washed,  are  especially 
adapted  for  polishing  compositions.  The  rubber  is 
mixed  with  150  to  200  per  cent,  of  this  powder, 
and  the  entire  mass  is  vulcanized  by  adding  10  to 
15  per  cent,  of  the  weight  of  rubber  of  sulphur 
to  it,  and  subjecting  it  to  the  heating  process. 

Grinding  compositions  may  be  prepared  by  using 
powdered  glass,  pumice-stone,  flint,  or  emery.  The 
masses  containing  powdered  glass  or  pumice-stone, 
being  the  softest,  may  be  used  for  grinding  brass  or 
bronze,  and  those  containing  powdered  flint,  for 
grinding  steel.  The  masses  containing  emery  may 
be  even  used  for  grinding  precious  stones,  as  emery 
is  the  hardest  body  next  to  the  diamond. 

To  change  the  hard  bodies — glass,  flint,  and 
emery — into  fine  powder,  it  is  necessary  to  make 


142    INDIA  RUBBER,  GUTTA  PERCH A,  BALATA. 

them  red  hot,  and  to  throw  them  while  in  this  con- 
dition into  cold  water.  They  become  very  brittle 
in  consequence  of  the  quick  cooling  off,  and  can 
then  be  ground  into  fine  powder  without  great 
difficulty. 

If  the  grinding  composition  is  to  be  subjected  to 
considerable  wear,  it  is  advisable  to  add  to  the 
rubber,  besides  the  powder  of  the  hard  body,  some 
sulphur,  and  to  heat  the  mass  sufficiently  to  change 
the  rubber  into  hard  rubber. 

It  is  merely  a  matter  of  choice  what  form  is  to  be 
given  to  the  grinding  and  polishing  compositions. 
Revolving  circular  disks,  against  which  a  piece  of 
vulcanized  rubber  is  pressed,  are  very  suitable  for 
sharpening  and  polishing  table  knives.  If  a  knife 
is  placed  between  the  disk  and  the  piece  of  rubber 
it  will  appear  polished  or  ground  after  a  few  revo- 
lutions of  the  disk. 

For  manufacturing  purposes,  especially  for  metal 
workers,  it  is  best  to  give  to  the  grinding  or  polish- 
ing masses  the  form  of  ordinary  grindstones,  that 
is,  that  of  circular  disks. 

The  quantity  of  powdered  hard  substances  to  be 
incorporated  with  the  rubber,  may  be  a  very  large 
one,  especially  if  hard  rubber  is  used,  and  may 
amount  to  as  much  as  four  times  its  weight. 

Piubber  enamel.  Hard  rubber,  on  account  of  its 
elasticity  and  toughness,  is  well  adapted  for  coating- 
articles  of  metal  which  are  to  be  protected  against 
rust.  For  the  purpose  of  coating  metal  with  a  thin 
layer  of  hard  rubber,  it  is  brushed  over  with  a  solu- 


RUBBER    COMPOUNDS.  143 

tion  of  rubber  in  benzine  or  petroleum,  and  is  then 
dusted  with  powdered  sulphur.  Both  operations 
are  repeated  after  the  first  coat  has  become  dry. 
The  articles  coated  in  this  manner  are  quickly 
heated  to  a  temperature  of  from  320°  to  338°  F., 
when  the  well-known  reciprocal  action  between 
sulphur  and  rubber  takes  place,  and  they  will  come 
out  with  a  coat  of  hard  rubber.  Defective  places 
in  the  coating  can  be  repaired  by  repeating  the 
brushing  over  with  the  rubber  solution,  dusting 
with  sulphur  and  heating. 

If  it  is  desired  that  the  coat  should  show  an 
entirely  uniform  black  color,  it  is  advisable  to  dust 
the  article  with  a  fine  black  pigment  after  it  has 
been  dusted  with  sulphur.  Frankfort  black  can  be 
especially  recommended  for  this  purpose,  as  it  forms 
an  entirely  dry  powder  which  can  be  readily  and 
completely  dusted  away,  which  is  not  the  case  with 
the  majority  of  black  pigments,  for  instance,  lamp- 
black, as  more  or  less  tarry  matter  always  adheres 
to  them. 

The  following  process  may  be  recommended  for 
preparing  colored  enamels  of  somewhat  greater 
thickness.  An  entirely  clear,  but  rather  thick  solu- 
tion of  rubber  is  prepared.  This  is  intimately 
mixed  with  about  12  per  cent,  of  the  weight  of  the 
rubber  originally  used  of  the  finest  powdered  sul- 
phur and  the  coloring  substance  to  be  incorporated. 
The  mass  obtained  in  this  manner  should  have  a 
consistency  equal  to  thick  oil  paint.  Should  it  be 
too  thick  to  allow  of  it  being  evenly  applied  with  a 


144    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

brush,  it  may  be  reduced  with  oil  of  turpentine,  or, 
in  case  it  is  too  thin,  this  may  be  remedied  by  an 
addition  of  coloring  matter. 

If  benzine  or  carbon  disulphide  has  been  used  as 
a  solvent,  it  will  be  very  difficult,  on  account  of  the 
great  volatility  of  these  fluids,  to  evenly  apply  the 
mass  with  a  brush.  It  is  therefore  best  to  allow  the 
rubber  to  swell  up  in  benzine  or  carbon  disulphide, 
and  effect  complete  solution  with  oil  of  turpentine 
or  rectified  petroleum. 

Bristle  brushes  are  used  to  coat  the  articles  with 
the  composition,  and  it  should  be  done  in  thin  but 
frequently  repeated  applications.  If  a  white  basis 
mass  is  used  marbled  designs  can  be  produced  by 
using  yellow,  red,  or  blue.  The  beauty  of  the  work 
will  of  course  depend  on  the  skill  of  the  workman. 

When  the  entire  coat  is  finished  it  is  dried,  which 
can  be  accelerated  by  exposing  the  article  to  a  tem- 
perature not  exceeding  212°  F.  In  case  the  enamel 
shows  defective  places  it  is  repaired  and  finally 
heated  at  a  temperature  of  320°  F.  The  rubber 
enamel  manufactured  in  this  manner  adheres  very 
tightly  to  metal,  and  will  take  a  very  high  degree 
of  polish.  As  it  will  stand  a  temperature  of  over 
392°  F.,  it  can  be  advantageously  used  for  enamel- 
ing the  exteriors  of  self-feeding  stoves,  etc. 

Deodorizing  vulcanized  rubber.  All  articles  manu- 
factured from  vulcanized  rubber  possess  a  disagree- 
able odor,  perceptible  even  after  the  articles  have 
been  in  use  for  months.  As  this  odor  is  very 
repugnant  to  some  persons,  who  will  not  use  rubber 


KUBBER   COMPOUNDS.  145 

articles  simply  for  this  reason,  it  becomes  a  matter 
of  importance  to  remove  this  objection,  especially 
with  articles  intended  for  personal  use — pocket 
books,  cigar  cases,  etc. 

Vulcanized  rubber  may  be  deodorized  in  various 
ways :  The  articles  are  either  exposed  to  a  constant 
high  temperature,  or  are  treated  with  animal  char- 
coal. While  heating  will  remove  the  odor,  to  get 
entirely  rid  of  it,  it  must  be  continued  for  many 
days,  and  this  method  is,  therefore,  not  available  in 
practice.  On  the  other  hand,  animal  charcoal  pos- 
sesses in  a  high  degree  the  property  of  absorbing 
odor.  For  the  purpose  of  deodorizing  rubber  it 
should  be  used  in  the  form  of  powder. 

A  large  number  of  articles  may  be  deodorized  at 
one  time  by  treating  them  as  follows :  Cover  the 
bottom  of  a  sheet-iron  box  about  }  inch  deep  with 
powdered  animal  charcoal,  upon  which,  place  the 
articles.  Fill  in  the  spaces  between  them  with 
animal  charcoal  and  cover  with  a  layer  about  f 
inch  deep.  Upon  this  another  layer  of  articles  is 
laid,  and  so  on,  until  the  box  is  filled,  when  it  is 
placed  in  a  room  having  a  temperature  of  from 
140°  to  176°  F.,  and  left  there  from  3  to  8  hours, 
according  to  the  size  of  the  box. 

During  this  time  the  animal  charcoal  absorbs 
the  odor,  and  the  articles  become  entirely  deodor- 
ized. But  they  must  be  stored  in  a  special  room, 
as  they  would  again  absorb  the  odor  if  stored  with 
articles  not  deodorized.  In  the  course  of  time,  the 
animal  charcoal  loses  its  deodorizing  ability  and 
10 


146   INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

must  be  replaced  by  fresh  material,  but  it  can  be 
regenerated  by  calcining.  This  is  done  by  placing 
it  in  a  sheet-iron  cylinder  about  20  inches  long, 
and  closed  on  both  ends  by  tight-fitting  covers. 
The  upper  lid  should  have  a  hole  the  thickness  of 
a  straw  to  allow  the  gases  to  escape.  The  animal 
charcoal,  after  it  has  been  thoroughly  calcined, 
must  be  allowed  to  cool  off  before  the  cylinders  are 
opened,  as  it  would  burst  into  flame  and  be  con- 
sumedvif  exposed  to  the  air  while  hot. 

Desulphurized  vulcanized  rubber.  As  previously 
mentioned,  only  a  small  portion  of  the  sulphur — 
about  1  to  2  per  cent. — combines  chemically  with 
the  rubber,  the  greater  portion  being  only  mechan- 
ically mixed  with  it.  This  sulphur,  however,  be- 
comes effective  in  time  and  causes  the  articles  to 
become  brittle  and  hard  after  long  storage.  This 
defect  will  show  itself  especially  in  rubber  hose, 
which  becomes  so  hard  that  it  will  break  when  an 
attempt  is  made  to  bend  it.  To  prevent  this  evil 
the  excess  of  free  sulphur  is  removed  by  boiling 
the  vulcanized  rubber  in  caustic  soda  or  caustic 
potash  lye,  whereby  the  free  sulphur  is  gradually 
dissolved,  while  the  chemical  combination  of  sul- 
phur and  rubber  is  not  attacked. 

The  time  required  for  boiling  depends  on  the 
strength  of  the  lye  used  and  on  the  quantity  of  free 
sulphur  present.  The  best  plan  is  to  take  occasion- 
ally a  piece  of  the  rubber  from  the  boiler  and  by  it 
test  the  progress  of  desulphurization.  The  color  of 
desulphurized  rubber  closely  resembles  that  of  the 


RUBBER    COMPOUNDS.  147 

ordinary  product.  Therefore,  as  long  as  the  piece 
shows  the -characteristic  grayish  coloring  of  ordinary 
vulcanized  rubber,  the  mass  is  not  properly  desul- 
phurized, and  the  boiling  must  be  continued. 

Vulcanized  rubber,  from  which  the  excess  of  free 
sulphur  has  been  properly  removed,  only  requires 
washing  and  drying  after  it  has  been  taken  from  the 
lye,  and  is  then  a  product  which  may  be  called  the 
most  perfect  of  all  rubber  preparations,  as  it  remains 
not  only  entirely  soft  and  elastic  in  all  temperatures, 
but  does  not  become  hard  even  if  stored  for  a  long 
time,  and  has  no  odor  whatever.  It  is  well  adapted 
for  manufacturing  articles  for  surgical  or  scientific 
purposes  or  to  be  used  in  the  nursery  or  sick-room 
— nursing  nipples,  rubber  cloth  to  protect  bedding, 
etc.  It  is  also  an  excellent  material  for  gas-tubing, 
as  it  combines  great  pliability  with  perfect  imper- 
meability to  gas. 


CHAPTER  V. 

HARD    RUBBER. 

IT  has  previously  been  mentioned  that  when  vul- 
canized rubber  contains  too  much  sulphur,  and  is 
exposed  to  a  higher  'temperature  for  a  longer  time 
than  necessary  for  vulcanizing,  it  becomes  hard  and 
horn-like.  Hancock  observed  this  at  an  early  date, 
and  makes  mention  of  it  in  his  first  patent-specifica- 
tion. .  Goodyear  continued  the  experiments,  and 
some  years  later  patented  a  method  for  manufactur- 
ing, from  rubber  and  gutta-percha,  with  the  addition 
of  other  substances,  articles  which  were  formerly 
made  of  wood,  leather,  metal,  etc.,  and  which  at  the 
same  time  were  lighter  and  cheaper. 

Generally  speaking,  the  preparation  of  hard 
rubber  is  based  upon  the  same  principles  as  that  of 
vulcanized  rubber.  The  crude  rubber  is  softened, 
washed,  dried,  macerated,  mixed,  according  to  cir- 
cumstances, with  other  specially  suitable  varieties 
of  crude  rubber,  and  compounded  with  sulphur  and 
other  ingredients.  The  addition  of  sulphur  may 
amount  to  as  much  as  50  per  cent.  In  place  of  pure 
sulphur,  other  sulphur  combinations,  such  as  sul- 
phide of  antimony  or  sulphide  of  lead,  can  be  used. 
Goodyear  has  recommended  a  zinc  compound,  which 
is  prepared  as  follows  :  Solution  of  zinc  sulphate  or 
(148) 


HARD    RUBBER .  149 

acetate  is  precipitated  with  solution  of  liver  of  sul- 
phur, either  direct  or  after  the  latter  has  been  de- 
colorized by  the  introduction  of  sulphurous  acid. 
The  precipitate  thus  obtained  is  thoroughly  washed 
with  water  and  used  after  drying. 

Besides  sulphur,  other  substances  such  as  zinc- 
white,  whiting,  magnesia,  etc.,  may  be  added  to  the 
mass  while  being  treated  in  the  rolls,  the  proportion 
of  such  additions  depending  on  the  demands  made 
on  the  finished  material  as  regards  elasticity,  flexi- 
bility or  hardness,  as  well  as  color.  The  prepara- 
tory operations  require  still  greater  care  and  atten- 
tion than  in  the  preparation  of  soft  rubber,  as  a 
very  small  quantity  of  water  and  very  small  air 
bubbles  enclosed  in  the  mass  may  make  it  porous 
or  even  entirely  ruin  it  in  consequence  of  the  high 
temperature  to  which  the  material  is  later  on 
exposed. 

Hard  rubber  is  used  in  the  manufacture  of  many 
articles,  such  as  combs,  spindles,  shuttles  for  spin- 
ning and  weaving,  cigar  and  match  cases,  valves, 
pumps  for  corrosive  fluids,  surgical  instruments,  etc. 

The  rubber,  sulphur  and  other  ingredients  are 
combined  between  mixing  rolls,  the  operation  being 
continued  until  a  thoroughly  homogeneous  mass 
has  been  formed,  which  has  the  consistency  of 
dough,  and  can  be  shaped  into  all  possible  forms. 

The  prepared  crude  mass  is  rolled  into  plates  of 
various  thicknesses,  and  the  separate  articles  made 
from  them  by  pressing  in  moulds.  Small  boxes, 
spectacle  cases,  etc.,  are  moulded  over  solid  cores. 


150    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

Sometimes  larger  sheets  are  rolled  out,  vulcanized, 
and  then  worked  like  wood  or  horn,  with  a  lathe, 
or  saw  and  plane. 

To  prevent,  in  filling  the  moulds  with  the  pro- 
pared  mass,  air  bubbles  from  remaining  between  it 
and  the  mould,  En  gel,  according  to  a  German 
patent,  first  fills  the  mould  with  linseed  oil,  then 
presses  the  prepared  rubber  mass  into  the  mould  so 
that  in  vulcanizing,  the  small  remaining  portion  of 
the  oil  is  absorbed  by  the  rubber. 

Vulcanizing  hard  rubber  requires  either  one  or 
two  operations.  If  ordinary  articles  or  simple 
sheets  are  to  be  treated,  one  operation  suffices,  but 
for  more  complicated  shapes  it  is  advisable  to  per- 
form the  work  in  two  operations. 

If  vulcanizing  is  to  be  done  at  one  operation,  the 
articles  are  placed  in  the  heater,  and  heated  for 
several  hours — three  to  six — at  a  temperature  of 
302°  F.  Manufacturers  differ  in  their  statements 
about  the  degree  of  heat,  but  these  are  of  little  value, 
as  every  practical  man  will  soon  find  out  for  him- 
self. It  is  stated,  for  instance,  that  especially  excel- 
lent properties  are  given  to  hard  rubber  by  first 
heating  it  for  two  hours  at  230°  F.,  then  quickly 
raising  the  temperature  to  302°  F.,  and  keeping  it 
there  for  several  hours. 

By  this  process  articles  are  obtained  sufficiently 
vulcanized,  as  a  temperature  of  302°  F.  suffices  to 
convert  quite  thick  objects  into  hard  rubber  in  the 
course  of  several  hours,  but  it  is  difficult  to  under- 
stand the  object  or  effect  of  Ji eating  them  for  two/ 


HARD    RUBBER.  151 

hours  at  230°  F.,  as  sulphur,  as  is  well  known, 
only  fuses  at  235.4°  F.,  and  it  is  scarcely  worth 
while  to  talk  about  sulphur  producing  any  effect 
before  it  is  melted.  By  special  experiments  in  this 
line  it  has  been  ascertained  that,  even  after  the 
mass  had  been  heated  for  several  hours  at  a  tem- 
perature of  230°  F.,  by  far  the  greater  part  of  the 
sulphur  could  be  extracted  from  it  in  an  unaltered 
state  by  a  solvent,  this  being  a  sure  proof  that  no 
chemical  action  had  taken  place. 

Hard  rubber  suffers  considerable  contraction  in 
the  course  of  vulcanizing,  and  the  shrinkage  of  the 
articles  allows  of  their  removal  from  the  moulds  by 
a  gentle  tap.  The  shrinkage  being  uniform,  owing 
to  the  even  temperature,  the  articles  do  not  warp. 

Articles  of  a  not  especially  complicated  shape 
may  be  vulcanized  without  the  use  of  a  mould. 
Flat  articles  may  be  treated  without  further  prepar- 
ation by  laying  them  upon  iron  plates,  but  if  other 
articles  are  to  be  vulcanized  without  the  use  of 
moulds,  it  is  advisable  to  dust  them  over  with 
magnesia  or  powdered  chalk,  and  to  place  them  in 
sheet-iron  boxes  filled  with  fine  sand  in  such  a 
manner  that  the  articles  are  completely  covered  by 
it  on  all  sides.  The  sand  prevents  the  articles  from 
collapsing  during  the  first  period  of  heating,  an 
event  which  it  would  be  very  difficult  to  avoid 
without  it. 

By  the  above  process  skilled  workmen  can  vul- 
canize and  finish  in  one  operation  quite  complicated 
articles,  with  a  very  small  percentage  of  defective 


152    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

products.  However,  to  prevent  any  possible  failure 
it  is  advisable  to  divide  the  vulcanizing  process  into 
several  operations. 

In  this  case  the  first  operation,  at  a  temperature 
of  about  293°  F.,  lasts  but  one  hour.  The  articles 
then  acquire  a  considerable  degree  of  solidity,  and 
can  be  taken  from  the  moulds  to  undergo  inspection. 
The  perfect  pieces  are  immediately  put  back  in  the 
heater  and  finished  without  further  manipulation, 
but  those  showing  defective  places,  cracks,  holes, 
etc.,  are  repaired  with  a  dough-like  mass  of  rubber, 
and  heated  for  another  hour,  when  they  are  again 
inspected  and  repaired,  if  necessary,  and  heated  for 
another  hour — this  alternate  inspection,  repairing, 
and  heating  being  continued  until  the  articles  can 
pass  for  finished  goods. 

Hard  -rubber,  prepared  from  crude  rubber  and 
sulphur  only,  has  a  black  color,  and  takes  a  very 
high  degree  of  polish.  Articles  manufactured  from 
this  material,  although  black,  can  also  be  colored 
any  desired  shade. 

A  distribution  of  the  coloring  substances  through 
the  entire  mass  has  the  advantage  of  considerably 
increasing  its  weight,  but  it  also,  to  a  great  extent, 
injures  its  properties.  To  give  hard  rubber  any 
desired  color  without  altering  its  internal  properties 
two  methods,  which  may  be  designated  as  "dusting," 
and  "plating,"  or  "enameling,"  are  made  use  of, 
both  being  well  adapted  for  the  purpose. 

Dusting  is  done  as  follows  :  After  the  article  has 
been  shaped  from  the  prepared  crude  material,  it  is 


HARD    RUB] 


thickly  dusted  over  with  a  finely-powdered  coloring- 
matter  contained  in  a  linen  bag.  The  mould  into 
which  the  article  is  to  be  pressed  must  first  be  uni- 
formly dusted  over.  After  vulcanizing  the  article 
should  show  a  uniform  coloring.  Any  defect  is  re- 
paired by  repeating  the  dusting  over  and  reheating. 

Articles  of  an  entirely  uniform  color  can  be  ob- 
tained by  plating  or  enameling  as  follows  :  A  mass 
is  prepared  from  crude  rubber  and  sulphur  in  the 
usual  manner  by  rolling,  the  coloring  matter  being 
at  the  same  time  incorporated  with  it.  Rolling  is 
continued  until  a  uniformly-colored  paste  is  ob- 
tained. 

The  paste  thus  colored  is  rolled  into  a  sheet  about 
half  as  thick  as  the  sheet  to  be  enameled,  and  if 
only  one  side  of  the  latter  is  to  be  treated,  the  two 
sheets  are  laid  one  upon  the  other  and  rolled  out  to 
the  thickness  acquired  for  the  articles  to  be  made. 

If  the  rubber  is  to  be  enameled  on  both  sides,  a 
plain  sheet  is  placed  between  two  colored  ones.  In 
this  manner  a  different  color  may  be  provided  on 
each  side,  and  an  enamel  of  any  desired  thickness 
applied.  The  thinner  the  enamel,  the  thicker,  of 
course,  the  enclosed  plain  sheet  must  be. 

Frequently  the  smaller  portion  of  articles  called 
hard  rubber  consists  of  actual  rubber,  various  indif- 
ferent substances,  such  as  chalk,  magnesia,  zinc- 
white,  etc.,  being  added  for  the  purpose  of  increas- 
ing the  weight.  If  these  admixtures  are  intended  to 
impart  a  certain  color  to  the  rubber,  care  must  be 
had  not  to  use  a  coloring  matter  which  may  be 


154    INDIA  RUBBER,  GUTIA  PERCH  A,  BALATA. 

affected  by  sulphur,  otherwise  the  coloring  may  turn 
out  the  reverse  of  what  was  intended.  For  this 
reason  coloring  substances  containing  lead,'  such  as 
white  lead,  chrome  yellow,  etc.,  must  be  avoided, 
since  lead  readily  combines  with  sulphur,  forming 
black  sulphide  of  lead,  and  in  this  case  black  instead 
of  white  or  yellowish  masses  would  be  obtained. 
What  has  been  said  about  lead  compounds,  applies 
also  to  coloring  substances  containing  copper. 

Lakes,  prepared  from  organic  substances  and 
alumina,  as  well  as  zinc  colors,  may  be  used  for 
coloring  hard  rubber  without  any  further  prepara- 
tion, except  that  the  lakes  must  be  perfectly  dry 
before  they  are  incorporated  with  the  mass.  If 
used  moist,  the  water  contained  in  them  is,  during 
the  vulcanizing  process,  converted  into  steam  and 
the  bubbles  thus  formed  cause  the  mass  to  bulge 
up  and  the  surface  to  become  rough,  while  the 
interior  will  not  be  compact  but  porous. 

The  waste  resulting  in  moulding  tho  articles  is 
immediately  kneaded  together,  passed  through  be- 
tween the  rolls,  and  may  then  be  used  in  the  manu- 
facture of  other  articles.  But  the  waste  from  hard 
rubber,  i.  e.,  after  it  has  been  vulcanized,  can  only 
be  utilized  for  the  preparation  of  lacquer,  which 
will  be  referred  to  later  on. 

The  best  plan  is  to  shape  the  articles  by  pressing 
or  stamping  them  from  the  mass,  as  there  is  much 
less  waste  than  when  preparing  sheets  from  which 
the  articles  are  to  be  manufactured. 

The  hardness  and  elasticity  of  hard  rubber  prin- 


HARD    RUBBER.  155 

cipally  depend  on  the  quantity  of  sulphur  which 
has  been  added  to  the  crude  material.  Below  a  few 
receipts  adapted  for  the  purpose  are  given. 

Articles  sufficiently  elastic  and  pliable,  so  that 
they  will  not  break,-  even  when  sharply  bent,  can 
be  made  from  the  following  composition  : 

Parts. 

Rubber 86  to  88 

Sulphur 14  to  12 

This  is  especially  well  adapted  for  manufacturing 
combs  and  such  thin  articles  as  are  to  possess  a  high 
degree  of  elasticity  and  considerable  solidity. 
By  mixing  together : 

Parts. 

Rubber 76  to  80 

Sulphur 24  to  20 

a  mass  is  obtained  which,  in  regard  to  elasticity,  is 
nearly  equal  to  the  foregoing,  but  is  somewhat 
more  fragile. 

The  larger  part  of  the  articles,  as  combs,  etc., 
sold  as  hard  rubber  are  made  of  a  composition  re- 
sembling the  latter,  but  containing  more  sulphur 
and  consequently  are  much  cheaper. 

Ebermayer  has  examined  hard  rubber  combs 
from  various  factories  and  found  that  their  elasticity 
is  conditional  on  the  content  of  sulphur.  Thus  a 
mass  with  11.95  per  cent,  sulphur  could  be  readily 
bent  but  not  broken,  while  a  mass  with  21.46  per 
cent,  could  be  broken  only  with  difficulty,  and  one 
containing  28.25  per  cent,  was  extremely  brittle 
and  hard. 


156    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

When  great  hardness  and  solidity,  with  but  little 
elasticity  are  required,  as  in  a  material  suitable  for 
knife  handles,  rollers,  buttons,  tool  handles,  door 
knobs,  lock  plates,  etc.,  the  percentage  of  sulphur  is 
increased  and — 

Parts. 

Rubber    .....     65  to  76 
Sulphur  .         .         .         .         .35  to  24 

form  the  best  compositions  for  such  purposes. 

It  is  a  remarkable  fact  that  some  resins,  although 
quite  brittle  by  themselves,  impart  a  certain  elastic- 
ity to  hard  rubber.  Shellac  is  especially  effective 
in  this  respect.  It  can  be  used  either  bleached  or 
unbleached  (the  so-called  ruby  shellac).  The  latter 
is  to  be  preferred  for  articles  of  a  dark  color,  as  it  is 
far  cheaper  than  the  bleached  article,  and  answers 
the  purpose  equally  well. 

The  shellac  should  be  powdered  as  fine  as  pos- 
sible, and  intimately  mixed  with  the  rubber  by  con- 
tinuous rolling.  A  piece  of  shellac  large  enough  to 
be  visible  to  the  naked  eye  would  be  sufficient  to 
spoil  the  appearance  of  the  article.  Hard  rubber 
will  bear  the  admixture  of  a  large  quantity  of  shel- 
lac, and  in  some  cases  an  amount  equal  to  that  of 
the  crude  material  may  be  used. 

A  composition  consisting  of: 

Parts  by  weight. 

Rubber    ' 88 

Sulphur 12 

Shellac  50 


HARD    RUBBER.  157 

was  formed  into  sticks  having  a  cross  section  of 
0.155  square  inch,  which  could  be  bent  to  a  consid- 
erable extent  after  they  had  been  vulcanized,  but 
were  at  the  same  time  so  elastic  that  the  sticks 
always  sprung  back  to  their  original  straight  form. 
The  rubber  was  so  hard  that  thin  shavings  could 
be  cut  from  it  only  with  a  very  sharp  knife.  In 
consequence  of  these  properties  this  variety  of  hard 
rubber  furnishes  an  excellent  material  for  the  man- 
ufacture of  bobbins  and  shuttles,  as  these  can  be 
made  so  thin  that  their  sides  are  scarcely  thicker 
than  thin  paste-board. 

Hard  rubber  can  be  used  with  great  advantage  for 
making  bowls  for  silver-plating  baths,  spatulas, 
rollers  and  other  utensils  used  by  photographers, 
also  for  stoppers  and  caps  of  bottles  containing 
corrosive  fluids. 

Newton  prepares  buttons,  knife  handles,  etc.,  by 
mixing  gutta  percha,  with  or  without  rubber,  with 
an  equal  weight  of  sulphur  and  exposing  the  mix- 
ture to  a  temperature  of  from  248°  to  302°  F.  For 
every  pound  of  gutta  percha  may  be  added  J  to  f  Ib. 
of  a  mixture  of  chalk,  gypsum,  shellac  and  resin. 

Johnson  uses  a  mixture  of  sulphur  1  part,  zinc 
oxide  9  parts,  and  rubber  9  parts  for  the  manufac- 
ture of  brushes,  curry-combs,  etc. 

Hard  rubber  is  much  used  in  the  manufacture  of 
black  ornaments,  such  as  brooches,  earrings,  brace- 
lets, chains,  etc.,  which  resemble  jet  and  even  onyx, 
when  finely  polished.  But  as  the  pieces  come 
more  or  less  dull  and  dead  from  the  moulds  the 


158   INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

require  polishing,  which  is  clone  either  upon  the 
lathe  or  by  means  of  cloth  or  felt  wheels,  and 
sometimes  with  the  use  of  a  fine  polishing  agent. 
Since  this  mode  of  polishing  considerably  increases 
the  cost  of  the  articles,  it  lias  been  endeavored  to 
find  a.  process  which  renders  polishing  entirely 
superfluous  or  at  least  facilitates  it.  The  use  of 
glass  moulds  or  lining  the  iron  moulds  with  thin 
tin-foil  has  yielded  good  results  in  this  direction. 

Many  rubber  articles  require  a  combination  be- 
tween hard  and  soft  rubber,  between  soft  and  semi- 
hard,  semi-hard  and  entirely  hard,  or  between  all 
three.  Such  problems  are,  for  instance,  presented 
in  lining  iron  boilers  intended  for  the  reception  of 
acids  (montejus),  in  the  fabrication  of  coatings  for 
rolls,  especially  of  larger  dimensions,  such  as  are 
used  in  the  manufacture  of  paper  and  leather,  and 
in  finishing  cotton  goods,  and  in  the  manufacture 
of  many  other  smaller  articles.  The  correct  and 
suitable  solution  of  such  problems  requires  besides 
close  supervision  of  the  workmen,  very  careful  se- 
lection of  the  varieties  of  crude  rubber  and  admix- 
tures to  be  used,  as  well  as  many  years'  experience 
in  vulcanizing. 

The  physical  and  chemical  properties  of  hard 
rubber  are  entirely  different  from  those  of  crude 
rubber.  It  is  black,  entirely  without  odor,  horn- 
like, and  not  unlike  hard  wood  or  ivory.  It  is 
dielectric,  but  becomes  electric  by  vigorous  rub- 
bing. Cold  water,  light  and  atmospheric  air,  have 
no  effect  upon  it.  It  does  not  oxidize.  In  boiling 


HARD    RUBBER.  159 

water,  however,  it  becomes  soft  and  flexible.  To- 
wards solvents,  which  completely  dissolve  crude 
rubber  and  partly  vulcanized  soft  rubber,  it  is  en- 
tirely indifferent,  and  it  resists  acids  to  a  high  de- 
gree. Exposed  for  some  time  to  dry  temperatures 
of  above  392°  F.,  it  does  not  become  firat  sticky 
like  natural  crude  rubber,  nor  melt  like  soft  vul- 
canized rubber,  but  commences  to  carbonize  with- 
out having  yielded  an  intermediate  product. 

Preparation  of  artificial  ivory.  For  many  years 
chemists  have  endeavored  to  prepare  a  substance  to 
serve  as  a  substitute  for  ivory,  which  is  every  year 
becoming  scarcer  and  dearer.  Their  attention  was 
principally  directed  to  compositions  writh  glue  as  a 
base,  to  which  were  added  finely  powdered  white 
substances,  and  such  bodies  as  would  make  the  glue 
insoluble ;  the  salts  of  alumina  and  tannin  being 
chiefly  used  for  this  purpose.  It  cannot  be  denied 
that  the  process  of  preparing  such  masses  has  been 
successful  as  far  as  their  external  appearance  is 
concerned,  it  being  scarcely  possible  to  distinguish 
them  from  genuine  ivory.  But  they  lack  one  of 
the  principal  properties  of  the  genuine  article, 
namely  that  of  combining  great  elasticity  with 
solidity. 

It  has  been  tried  to  utilize  rubber  for  preparing  a 
mass  which  would  possess  as  nearly  as  possible  all 
the  properties  of  ivory,  and  these  experiments  have 
been  so  successful  that  substances  are  now  obtained 
which  can  be  employed  for  manufacturing  a  large 
number  of  articles  formerly  made  of  ivory.  But 


160    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

they  cannot  take  the  place  of  the  genuine  material 
where  elasticity  combined  with  great  solidity  is  a 
requisite.  Many  attempts  have  been  made  to 
manufacture  billiard  balls  from  such  composition, 
but  they  have  never  been  very  successful,  the  balls 
in  a  short  time  becoming  full  of  cracks,  and  break- 
ing even  when  but  gently  struck. 

For  the  preparation  of  an  elastic  mass  a  certain 
percentage  of  pure  rubber  must  be  added,  but  the 
resulting  product  is  not  of  a  sufficiently  light  color. 

It  may  here  be  mentioned  that  many  products 
are  sold  as  artificial  ivory  which  contain  but  a 
small  quantity  of  rubber  or  gutttf-pcrcha,  foreign 
substances,  which  impart  weight,  being  the  chief 
components.  The  same  may  be  said  of  compo- 
sitions sold  as  hard  rubber  which  contain  less  than 
33  per  cent,  of  rubber. 

Every  imaginable  kind  of  bleaching  agent  lias 
been  tried  and  recommended  for  decolorizing  and 
bleaching  rubber,  but  no  process  has  been  entirely 
successful,  and  it  may  justly  be  said  that  with  the 
means  at  present  at  our  command  it  is  impossible  to 
obtain  results  entirely  satisfactory.  If  rubber  be 
treated  with  a  bleaching  agent  which  exerts  any  kind 
of  effect  upon  it,  it  will  acquire  a  lighter  color — a 
very  light  yellowish-brown — but  a  chemical  change 
will  at  the  same  time  take  place,  and  the  mass 
bleached,  for  instance,  with  chlorine,  cannot  be 
called  rubber  any  longer. 

Several  methods  have  been  published,  by  which 
it  is  claimed  rubber  can  be  bleached  without  suffer- 


HARD    RUBBER.  161 

ing  a  chemical  change ;  but  on  testing  these 
methods,  the  result  was  always  the  same,  namely, 
the  bleached  product  did  not  possess  the  properties 
of  rubber.  Nearly  all  these  methods  amount  to 
the  same  thing,  namely,  that  the  rubber  is  allowed 
to  swell  up  very  much — complete  solution  not  be- 
ing necessary — and  chlorine  be  introduced  into  the 
swelled-up  substance.  The  most  suitable  solvents 
for  the  purpose  are  carbon  disulphide,  benzene  and 
rectified  petroleum,  though  chloroform  and  oil  of 
turpentine  have  also  been  recommended. 

For  treating  rubber  with  chlorine  a  special  appa- 
ratus is  required.  This  consists  of  a  wooden  vat 
lined  with  lead.  It  should  have  a  lid  or  cover 
lined  with  lead  and  capable  of  being  secured  air- 
tight. In  the  centre  of  the  lid  or  cover  is  a  revolv- 
ing shaft  connected  with  a  stirring  apparatus  made 
of  leaden  rods.  The  pipe  conducting  the  chlorine 
reaches  to  the  bottom  of  the  vat,  and  a  funnel  pro- 
vided with  a  stop-cock  is  fitted  into  the  cover  to 
admit  new  fluid  when  required.  A  small  pipe  is 
fitted  into  the  cover  and  passed  into  a  tank  of  water 
adjoining  the  vat,  for  the  escape  of  the  chlorine. 
Fig.  10  shows  the  arrangement  of  the  apparatus. 
The  chlorine  enters  through  C  ;  R  is  the  stirring 
apparatus  ;  J  is  the  funnel ;  A  the  escape  pipe  for 
the  chlorine ;  H  is  a  stop-cock  in  the  bottom  of  the 
vat,  covered  inside  with  a  leaden  sieve. 

The  rubber,  cleansed  and  cut  in  small  pieces,  or, 
still  better,  in  shreds,  is  placed  in  the  vat,  which  is 
then  closed,  and  the  solvent  poured  in  through  the 
11 


162        INDIA    RUBBER,  GUTTA    PERCHA,  BALATA. 

funnel  J.  The  stirring  apparatus  R  is  started  and 
kept  in  motion  until  solution  is  complete.  The 
chlorine  is  then  introduced  and  allowed  to  flow 
until  its  escape  is  noticed  from  the  pipe  A.  Alco- 
hol equal  in  volume  to  that  of  the  solvent  is  intro- 
duced into  the  vat  through  the  funnel  J,  which 

FIG.  10. 


causes  the  bleached  rubber  to  be  separated  and  pre- 
cipitated in  a  slimy  condition.  The  solution  is 
constantly  stirred  to  permeate  it  with  the  alcohol. 
The  stop-cock  H  is  then  slightly  opened  to  allow 
the  fluid  to  run  off.  The  alcohol  and  original 
solvent  are  finally  separated  by  distillation. 

The  apparatus  above  described,  though  very 
effective,  is  somewhat  obsolete,  since  for  the  prepa- 
ration of  chemical  products  in  general  and  espec- 
ially of  chlorine,  clay  vessels  are  now  made  in 


HARD   RUBBER.  163 

numerous  factories  which  are  cheaper  and  just  as 
effective  as  wooden  vats  lined  with  lead. 

As  has  been  stated,  rubber  bleached  in  the 
manner  above  described  is  of  a  brownish-yellow 
color,  and  should  be  immediately  worked,  as  it  is 
quite  soft  when  it  comes  from  the  bleaching  appa- 
ratus, and  can  be  easily  compounded  with  ad- 
mixtures. 

According  to  an  American  process  2  Ibs.  of 
rubber  are  dissolved  in  a  suitable  vessel  in  4  Ibs. 
of  chloroform.  The  solution  is  allowed  to  clear  by 
settling,  and  ammonia  is  then  introduced  to  satura- 
tion. When  the  rubber  is  completely  bleached, 
which  is  ascertained  by  frequently  examining  a 
sample,  the  solution  is  washed  with  hot  water  in  a 
vat  provided  with  a  stirring  apparatus,  to  remove 
all  traces  of  ammonia  and  chloroform.  The  sepa- 
rated rubber  forms  a  spongy  mass  which  is  squeezed, 
pressed,  dried  and  mixed  with  sufficient  chloroform 
to  form  a  thick  dough.  This  dough  is  intimately 
compounded  with  enough  phosphate  of  lime  or 
carbonate  of  zinc  to  form  a  mass  having  the 
appearance  of  damp  flour,  which  is  pressed  in  hot 
moulds.  The  articles  taken  from  the  moulds  may 
be  further  worked  in  the  turning  lathe.  By  adding 
suitable  coloring  matters  with  the  phosphate  of 
lime,  imitations  of  coral,  enamel,  etc.,  can  be 
prepared. 

The  simplest  method  of  bleaching  rubber  for  pre- 
paring artificial  ivory  is  to  treat  it  in  the  usual 
manner,  and  to  form  thin  bands  from  it  by  passing 


164   INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

it  through  the  rolls.  These  are  allowed  to  fall  into 
a  roomy  vat,  provided  with  a  cover,  and  containing 
water  saturated  with  chlorine. 

By  using  the  rubber  in  the  form  of  thin  bands, 
the  bleaching  process  goes  on  quite  rapidly,  and 
when  complete,  it  is  only  necessary  to  wash  the 
mass  several  times  in  hot  water  to  free  it  from  the 
adhering  chlorine.  It  is  advisable  to  add  a  small 
quantity  of  sodium  hyposulphite  (1  per  cent,  of  the 
salt  is  sufficient)  to  the  first  washing  water,  as  this 
salt  has  the  effect  of  removing  every  trace  of 
chlorine  which  may  still  be  present.  If  any  of  the 
chlorine  were  to  remain  it  would  exert  an  injurious 
effect  afterwards  when  the  material  has  to  be 
worked  in  machines  constructed  of  metal. 

The  best  plan  is  to  subject  the  bleached  mass  to 
further  treatment  immediately  after  it  has  been 
washed,  as  it  is  then  very  plastic.  But  if  it  is  not 
desired,  nor  possible  to  use  the  mass  at  once,  it  is 
advisable  to  moisten  it  with  some  carbon  disulphide 
or  benzene  and  to  let  it  remain  for  some  time  in  a 
hermetically  closed  vessel.  A  small  quantity  of 
the  solvent  will  cause  the  mass  to  swell  up  some- 
what, and  it  can  then  be  worked  with  greater  ease. 

The  next  operation  for  preparing  artificial  ivory 
is  to  incorporate  several  substances  with  the  plastic 
mass.  Either  whiting,  oxide  of  zinc  or  white 
lead  is  used  for  producing  a  white  material.  Arti- 
ficially prepared  sulphate  of  baryta  (the  blanc  or 
fix  permanent  white  used  as  a  coloring  substance 
by  the  manufacturers  of  wall  papers)  is  also  a  very 


HARD    RUBBER.  165 

suitable  material  for  the  purpose.  Articles  colored 
by  pigments  containing  white  lead,  lose  their  white 
color  in  time  and  turn  gray. 

The  colored  masses  are  worked  in  different  ways, 
either  direct  or  indirect.  If  the  direct  method  is 
chosen,  the  artificial  ivory  is  immediately  pressed 
into  hot  moulds,  but  sharp  impressions  can  only  be 
obtained  by  using  a  very  high  pressure.  Many 
elegant  articles  can  be  prepared  in  an  inexpensive 
mamier  by  this  method,  provided  it  is  not  absolutely 
necessary  that  the  substance  should  be  entirely 
homogeneous.  Knife  handles,  buttons,  etc.,  may  be 
prepared  by  direct  pressing. 

For  solid,  but  at  the  same  time  non-elastic 
articles,  it  is  best  to  use  the  indirect  method,  that  is 
to  say,  the  mass  is  formed  into  cubes,  and  the 
articles  are  shaped  from  them  by  the  lathe,  etc. 
Therefore  the  preparation  of  artificial  ivory  must  be 
regulated  by  the  use  intended.  For  instance,  the 
material  for  billiard  balls  should  undergo  less  pres- 
sure than  that  for  making  thin  sheets. 

The  greater  part  of  the  numerous  receipts  given 
for  preparing  artificial  ivory,  are  of  no  special  value, 
as  its  quality  depends  so  much  upon  the  rubber 
used,  the  duration  of  the  chlorine  treatment,  etc. 
According  to  many  of  the  receipts,  masses  are  made 
resembling  vulcanite,  by  using  sulphur  and  gutta- 
percha  in  addition  to  rubber,  and  heating  them  to 
302°  to  320°  F. 

Jacobsen  gives  an  American  receipt,  according  to 
which  a  mass  for  artificial  ivory  consists  of  the 
following  substances : 


166    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

Parts. 

Rubber 100 

Sulphur  ......       45 

Gutta-percha 10 

The  mass  is  heated  to  314.6°  F. 

While  it  has  been  considered  of  interest,  for  the 
sake  of  completeness,  to  give  a  description  of  the 
manufacture  of  artificial  ivory  from  rubber,  with 
the  present  high  prices  of  the  latter  material  the 
product  is  not  remunerative,  especially  as  at  the 
best  it  is  an  imitation,  which  lias  many  defects. 
Besides,  masses  are  now  prepared  from  celluloid, 
which  as  regards  their  properties,  resemble  more 
closely  ivory  than  the  best  rubber  compositions, 
and  are  much  cheaper. 


CHAPTER  VI. 

MANUFACTURE    OF    ARTICLES    FROM    SOFT    RUBBER. 

WITH  the  exception  of  waterproof  stuffs,  the  man- 
ufacture of  rubber  articles  depends  upon  plastic 
manipulation,  the  greater  portion  of  the  work  being 
done  by  hand.  Actual  machinery  is  but  little 
used,  but,  on  the  other  hand,  a  great  variety  of 
rnoulds  arid  presses  are  employed. 

The  best  known  articles  in  general  use  made 
from  fine  cut  sheets  are  :  Nipples  and  fittings  for 
milk  bottles,  tobacco  pouches,  tubes  for  chemical 
laboratories,  and  the  many  articles  for  chirurgicai 
and  technical  purposes,  for  which  no  other  rubber 
material  is  as  suitable.  The  manufacture  of  these 
articles  depends  on  hand  work,  and  is  very  simple, 
because  the  cut  surfaces  of  the  sheets  produced  with 
a  knife,  die  or  scissors  when  pressed  together  adhere 
immediately,  this  being  still  more  the  case  if  a 
thin  coat  of  benzine  or  of  thin  rubber  solution  be 
first  applied  to  them  by  means  of  a  small  brush. 
Hence  it  is  only  necessary  to  cut  out  according  to 
a  pattern  with  scissors  or  a  knife  the  several  parts 
of  the  articles  to  be  manufactured,  or  when  large 
quantities  are  to  be  produced,  for  instance,  nipples, 
to  die  them  out  and  then  put  them  together  either 
by  hand  or  over  a  mould.  In  order  to  make  a 
(167) 


168    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

better  joint,  the  seams  are  either  smoothed  with  a 
paper  folder  or  hammered  with  a  light  hammer 
having  a  rounded  face,  over  a  mandrel  or  anvil  with 
a  rounded  surface.  Hollow  articles — balloons,  tubes, 
etc. — are  dusted  inside  with  talc  to  prevent  the  sides 
from  sticking  together.  The  vulcanization  of  these 
articles  is  also  a  very  simple  operation. 

Rubber  toys.  The  manufacture  of  these  articles 
has  become  quite  an  important  branch  of  the  rubber 
industry,  as  on  account  of  their  indestructibility  and 
softness  they  are  especially  adapted  for  children's 
use.  Human  figures,  for  instance,  are  made  from 
vulcanized  rubber  by  pressing  in  metallic  moulds, 
so  that  the  figure  is  obtained  in  two  halves,  each  a 
few  millimeters  thick.  These  are  joined  together 
by  rubber  solution,  so  that  they  form  a  hollow 
body,  and  are  then  heated.  As  the  enclosed  air 
expands  during  the  heating  process,  and  would  cause 
the  figure  to  burst,  a  small  hole  is  made  in  some 
part  of  the  latter  to  allow  the  air  to  escape.  The 
hole  is  later  on  closed  by  a  small  rubber  plug. 

Such  figures  are  also  made  from  sulphurized 
sheets  with  the  use  of  a  type-metal  mould.  The 
sheets  are  cut  according  to  patterns  with  a  pair  of 
scissors  in  such  a  manner  that  the  cut  surfaces  are 
slightly  sloping,  which  facilitates  their  adhesion. 
Before  entirely  closing  the  figure,  a  small  quantity  of 
water,  ammonium  carbonate,  or  another  substance 
which  at  the  temperature  of  heating  is  converted 
into  steam,  is  poured  in.  The  completed  figure  is  then 
brought  into  the  mould.  The  steam  evolved  exerts 


ARTICLES    FROM    SOFT    RUBBER.  169 

a  pressure  upon  the  rubber,  and  presses  it  into  all 
the  depressions  of  the  mould,  filling  the  latter  com- 
pletely. After  vulcanizing,  a  small  hole  is  made  in 
the  figure  to  admit  air,  as  otherwise  the  figure  would 
collapse  in  consequence  of  the  condensation  of  the 
steam  and  the  formation  of  a  vacuum. 

Rubber  balls  are  made  in  a  similar  manner.  Seg- 
ments of  a  sphere  are  first  cut  according  to  pattern 
from  rubber  sheet,  and  then  joined  together  to  a 
ball  in  a  plaster  of  Paris  mould.  In  order  to  make 
the  balls  very  elastic  they  are,  after  vulcanizing, 
filled  with  compressed  air.  When  taken  from  the 
moulds,  the  balls  are  perforated  with  a  fine  hollow 
needle,  and  air  is  forced  in  through  the  latter  by 
means  of  a  small  compression  pump  until  a  pressure 
of  two  or  three  atmospheres  is  indicated.  The 
needle  is  then  withdrawn,  and  the  hole  quickly 
closed  with  sulphurized  rubber,  which  is  vulcanized 
by  holding  a  hot  iron  close  to  it. 

For  larger  balls  with  thicker  walls,  a  higher  pres- 
sure may  be  used,  and  it  is  advisable  to  fill  the 
balls  on  a  cold  day  in  the  open  air,  since  the  air 
on  becoming  warm  acquires  greater  tension. 

The  so-called  velours,  or  velvet  balls,  are  made 
from  gray  rubber  mass,  then  coated  with  a  solution 
of  pure  Para  rubber,  and  before  the  latter  is  entirely 
dry  provided  with  velours  covering.  From  balls 
thus  treated  the  air  does  not  escape,  and  they  retain 
their  spherical  shape. 

Hollow  articles  of  any  desired  shape  can  also  be 
prepared  by  using  the  rubber  dough,  the  prepara- 


170    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

tion  of  which  has  been  described  in  a  previous 
chapter.  The  process  is  nearly  the  same  as  that 
employed  in  moulding  hollow  articles  from  plaster 
of  Paris.  The  moulds  used  for  the  purpose  may  be 
made  of  metal,  wood,  or  plaster  of  Paris,  but  when 
of  the  last  two  materials  they  must  be  coated,  before 
use,  with  linseed  oil  varnish,  the  coating  being  re- 
peated until  the  moulds  absorb  no  more  varnish. 

Moulds  consisting  of  more  pieces  than  one  are 
put  together  in  the  same  manner  as  those  used  for 
moulding  articles  from  plaster  of  Paris,  and  the 
rubber  dough  is  then  poured  into  the  hollow  part. 
In  doing  this  the  mould  is  swung  to  and  fro  in 
such  a  manner  that  the  interior  wall  is  covered 
with  the  thick  fluid  mass,  and  then  the  excess  of 
dough  is  allowed  to  run  off.  But,  with  some  ex- 
perience, the  latter  is  not  necessary,  as  a  skilled 
workman  can  estimate  the  exact  quantity  of  dough 
required  for  a  mould  of  a  certain  size. 

To  accelerate  the  evaporation  of  the  solvent  from 
the  dough,  it  is  advisable  to  fit  a  pipe  into  the 
mould  through  which  air  is  blown  into  the  interior. 
By  this  the  vapors  of  the  solvent  are  quickly  carried 
off.  Finally,  the  mould  is  placed  in  a  warm  room 
to  dry. 

A  suitable  quantity  of  finely  powdered  sulphur 
or  other  vulcanizing  agent  may  be  mixed  with  the 
dough  before  it  is  formed  into  articles,  and,  if  this 
has  been  done,  it  is  -only  necessary  to  place  the 
articles  which  remain  in  the  mould  in  the  heater  to 
vulcanize  them.  If  pure  rubber  dough  has  been 
used,  they  can  be  vulcanized  by  a  simple  process. 


ARTICLES    FROM    SOFT    RUBBER.  171 

For  tliis  purpose  they  are  dusted  with  finely 
powdered  sulphur,  and  some  of  it  is  also  blown  into 
the  interior  of  them.  They  are  then  heated  in  the 
usual  manner ;  or  they  are  vulcanized  by  using 
chloride  of  sulphur. 

Small  solid  balls  of  vulcanized  rubber  are  re- 
quired for  sewing  machines.  These  are  prepared 
from  sulphurized  rubber  and  heated.  A  peculiar 
process  is  used  in  many  factories  for  manufacturing 
them  from  pure  rubber.  A  block  of  the  latter  is 
pressed  against  a  grater,  which  revolves  as  quickly 
as  possible,  and  by  this  is  cut  into  exceedingly  fine 
shavings  which  can  easily  be  balled  together. 

Balls  are  formed  from  these  shavings  with  the 
hand.  They  are  tightly  pressed  in  metal  moulds, 
then  brought  into  a  somewhat  smaller  mould  and 
in  this  subjected  in  the  cold  to  as  strong  a  pressure 
as  possible.  They  are  very  compact,  and  must  be 
heated  to  104°  F.  to  restore  to  them  their  elasticity. 
Balls  manufactured  in  this  manner  are  especially 
adapted  for  bearers  under  powerful  stamping- 
presses,  as  they  drive  the  stamp  back  with  great 
force. 

The  small  toy  baloons  belong  also  to  the  special- 
ties of  the  rubber  industry.  Very  small  balloons 
are  made  from  clear  rubber  solution.  A  glass 
balloon  serves  as  a  mould.  A  certain  quantity  of 
solution  is  poured  into  this  and  distributed  over 
the  entire  inner  surface  by  swinging  the  mould  to 
and  fro,  and  the  excess  of  solution  is  then  allowed 
to  run  off.  When  nothing  more  drains  off  the 


172    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

mould  is  replaced  with  the  neck  uppermost  and  air 
is  blown  in  to  accelerate  the  evaporation  of  the 
solvent. 

To  detach  the  balloon  from  the  glass,  to  which  it 
adheres  quite  tenaciously,  the  lower  edge  of  it  is 
carefully  loosened  from  the  glass  and  then  air 
blown  in  between  the  film  and  the  glass.  The  thin 
film,  of  which  the  balloon  consists,  becomes  entirely 
detached  from  the  glass  and  can  be  removed  in  the 
form  of  a  bag. 

The  rubber  sheets  prepared  upon  glass  plates,  as 
described  in  a  former  chapter,  may  be  used  for 
somewhat  larger  balloons,  such  as  are  employed  at 
meteorological  stations  for  ascertaining  the  direction 
of  the  wind.  As  most  of  these  balloons  have  a 
volume  of  a  few  quarts  only,  they  are  generally 
filled  with  illuminating  gas  and  then  closed. 

Printing  rolls  for  use  in  dye  ivork,  etc.,  are  prepared 
with  the  simultaneous  use  of  pressure  and  heat  as 
follows  :  A  tube  made  of  a  sheet  of  sulphurized 
rubber  mass  is  tightly  drawn  over  the  roll  of  which 
a  cast  is  to  be  taken,  and  firmly  wrapped  around 
with  cotton  cloth  so  that  all  depressions  are  filled 
up.  The  entire  mass  is  then  vulcanized,  and  after 
heating  the  tube  is  withdrawn  and  turned  inside 
out. 

Letellier  and  Verstraat  make  the  rubber  jacket 
of  the  pressure  rolls  of  cloth  printing  machines  of 
two  layers.  The  metal  drum  is  first  wrapped 
round,  2  millimeters  thick,  with  cotton.  Upon  this 
is  brought  a  layer  of  hard  black  rubber  of  1.6 


ARTICLES    FROM    SOFT    RUBBER.  173 

specific  gravity,  and  this  is  coated  with  softer  rubber 
of  1.3  specific  gravity.  The  total  thickness  of  both 
layers  is  20  millimeters,  and  the  upper  layer  is 
accurately  turned  for  printing,  and  polished  with 
emery. 

Preparation  of  rubber  threads.  The  manufacture 
of  threads  forms  an  important  branch  of  the  rubber 
industry,  since  on  account  of  their  elasticity  and 
tenacity,  they  are  extensively  used  in  the  fabrication 
of  elastic  tissues.  How  extensive  this  use  is  may  be 
understood  from  the  fact  that  large  factories  are 
entirely  devoted  to  the  manufacture  of  materials 
from  which  the  elastic  webbing  for  shoes  is  made. 

Rubber  threads  may  be  prepared  according  to 
various  methods,  but  their  elasticity  and  toughness 
depends  on  the  raw  material  used.  It  may  here  be 
remarked  that  rubber  which  has  been  shredded, 
masticated,  and  then  brought  into  a  compact  mass 
by  rolling,  does  not  possess  the  solidity  and 
elasticity  of  the  raw  material,  and,  of  course, 
threads  manufactured  from  the  former  are  of  a 
poorer  quality  than  those  prepared  from  the  latter. 

Square  cords  from  crude  rubber.  The  best  quality 
of  rubber  in  the  form  of  bottles,  with  the  thickest 
sides  and  of  the  most  regular  shapes,  should  be 
selected  for  making  such  cords.  The  necks  of  the 
bottles  are  cut  off,  and  the  bowl  or  body  is  bisected 
by  a  cross-cut.  The  pieces  are  then  examined,  and 
only  those  having  an  entirely  uniform  appearance 
are  selected.  Pieces  showing  large  hollow  spaces,  or 
an  indication  of  the  presence  of  foreign  bodies,  must 
be  rejected,  they  being  unsuitable  for  the  purpose. 


174    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

The  next  step  is  to  convert  the  pieces  obtained  by 
cutting  up  the  bottles  into  smooth,  even  sheets. 
This  is  effected  by  softening  the  pieces  by  continued 
boiling  in  Avater,  and  then  placing  them  between 
level  iron  plates  in  a  powerful  press  and  subjecting 
them  to  strong  pressure  for  a  few  weeks,  the  press 
being  from  time  to  time  tightened.  As  a  low  tem- 
perature helps  to  make  the  rubber  more  compact,  it 
is  advisable  to  carry  on  the  work  of  cutting  threads 
in  winter,  and  to  place  the  presses  in  the  open  air. 

The  sheets  when  taken  from  the  press  should  be 
perfectl}7  smooth  and  of  uniform  thickness.  They 
are  then  brought  to  the  cutting  machine.  This 
consists  of  a  shaft  upon  which  the  sheet  is  fixed 
vertically  by  means  of  sharp  points.  The  shaft 
revolves  around  its  axis,  progressing  forward  at  the 
same  time.  A  knife,  moving  quickly  to  and  fro, 
cuts  a  spiral  band  from  the  sheet,  the  thickness  of 
the  band  depending  on  the  greater  or  smaller 
velocity  with  which  the  sheet  approaches  the  knife. 

A  stream  of  water  falls  steadily  upon  the  knife  to 
prevent  the  rubber  from  sticking  to  it.  The  long 
band  obtained  by  the  operation  is  then  cut  into 
square  cords.  In  many  factories  the  neck  and 
bottom  of  the  bottles  are  cut  off,  and  the  remainder 
softened  in  boiling  water,  then  drawn  over  a  wooden 
mandrel  covered  with  a  thin  layer  of  rubber.  This 
mandrel  while  revolving  is  raised  a  certain  distance 
and  moves  against  a  knife,  placed  vertically,  which 
cuts  a  spiral  band  from  the  rubber.  This  is  a 
simpler  manner  of  obtaining  a  band  of  crude  rubber, 


ARTICLES    FROM    SOFT    RUBBER.  175 

but  the  cords  cut  from  it  are  not  quite  so  solid  as 
those  manufactured  from  the  pressed  halves  of  the 
bottles. 

The  bands,  obtained  by  either  of  these  methods, 
are  now  cut  into  cords  or  threads  by  machines,  as 
they  do  the  work  with  much  more  regularity  than 
is  possible  by  hand,  and  save  a  great  deal  of  time. 

The  simplest  manner  of  cutting  the  bands  into 
threads  is  between  two  steel  rolls,  in  the  circumfer- 
ences of  which  are  grooves  as  broad  as  the  threads 
to  be  cut,  and  so  arranged  that  the  upper  roll  covers 
every  groove  in  the  lower  one.  The  sheet  of  rubber 
passing  through  between  these  rolls  is  cut  into  a 
corresponding  number  of  equally  wride  threads 
which  are  wound  upon  reels.  The  dividing  of  the 
sheet  of  rubber  by  this  machine  must  be  called 
crushing  rather  than  cutting,  and,  if  the  threads  are 
to  be  cut  smooth,  it  is  necessary  that  the  edges  of 
the  grooves  should  be  extremely  sharp. 

More  complicated,  but  more  effective,  is  the 
thread- cutting  machine,  consisting  of  a  horizontal 
shaft  'with  circular  knives,  separated  according  to 
the  width  of  the  threads  to  be  cut.  Above  this 
shaft,  holding  the  knives,  is  placed  a  roll  with 
narrow  grooves,  into  which  the  knives  penetrate 
slightly. 

A  pair  of  smooth  rolls  grasp  the  sheet  to  be  cut 
into  threads  and  carry  it  through  between  the 
grooved  roll  and  the  knives,  which  revolve  with  as 
much  velocity  as  possible,  and  out  the  sheet  into  a 
corresponding  number  of  threads.  They  are  then 


176    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

passed  through  between  glass  rods  and  wound  upon 
reels. 

Cutting  square  cords  from  prepared  rubber. 
Although  threads  cut  directly  from  the  raw  mater- 
ial are  toughest,  their  use  is  limited  to  certain  pur- 
poses, as  they  cannot  be  obtained  of  any  consider- 
able length,  and  have  the  further  disadvantage  of 
not  being  vulcanized.  Hence  for  the  manufacture 
of  long  threads  or  of  threads  from  vulcanized  rubber^ 
prepared  rubber,  either  by  itself  or  mixed  with  sul- 
phur for  vulcanizing,  has  to  be  used. 

The  sheet  from  which  long  vulcanized  threads 
are  to  be  cut  is  first  vulcanized  and  then  cut. 

At  the  present  time  long  threads  of  ordinary  or 
vulcanized  rubber  are  generally  prepared  from  tub- 
ing which  is  divided  by  a  spiral  cut.  The  tubing 
to  be  cut  is  fastened  upon  a  wooden  mandrel,  which 
fits  exactly  into  the  bore  of  the  tube,  and  this  is 
fastened  to  a  metal  screw  which  gradually  moves 
forward.  A  knife  moving  quickly  to  and  fro  cuts  a 
spiral  strip  from  the  tube,  the  width  of  the  strip 
depending  on  the  height  of  the  screw-thread.  Rec- 
tangular threads  are  obtained  by  using  a  screw  with 
threads  of  less  height  than  the  thickness  of  the  walls 
of  the  tubing. 

The  machines  for  cutting  threads  from  tubing 
have  recently  been  much  improved,  and  threads  of 
any  desired  thickness  can  now  be  prepared  by  using 
but  one  screw. 

But  in  whatever  manner  the  threads  may  be 
manufactured,  it  is  of  the  utmost  importance  that 


ARTICLES    FROM    SOFT    RUBBER.  177 

the  greatest  care  should  be  used  in  winding  them 
upon  reels  to  prevent  the  freshly  cut  threads  from 
sticking  together. 

Round  rubber  threads.  For  certain  purposes, 
round  threads  are  required.  They  can,  however, 
be  manufactured  only  from  rubber  which  has  been 
changed  into  a  plastic  mass  by  treating  it  with 
proper  solvents.  This  plastic  rubber  is  then  pressed 
through  a  metal  plate  provided  with  circular  holes. 

According  to  Aubert  and  Gerard's  process  the 
purified  rubber  is  cut  up  into  small  pieces  and 
brought  in  contact  with  carbon  disulphide,  alcohol, 
fusel  oil,  or  wood  spirit.  Neither  of  these  dissolves 
the  rubber,  but  they  disintegrate  its  particles,  so  that 
they  can  be  easily  manipulated  into  a  uniform  paste 
or  dough. 

The  following  is  a  very  suitable  mixture  for  this 
purpose : 

Parts. 

Rubber 100 

Carbon  disulphide        .         .         .         100 
Alcohol,  85  per  cent,  strong .         .  5 

The  substances  are  placed  in  a  hermetically  closed 
metallic  vessel,  and  allowed  to  stand  for  from  15  to 
18  hours.  The  mass  is  then  pressed  through  a  wire 
netting  with  close  meshes,  which  retains  the  parti- 
cles not  entirely  swelled  up.  The  plastic  mass, 
which  should  be  of  the  consistency  of  thick  paste,  is 
then  brought  into  the  moulding  apparatus. 

This  consists  of  a  cylinder  in  the  bottom  of  which 
12 


178   INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

are  fitted  a  number  of  cone-shaped  tubes  the  bore* 
which  corresponds  to  the  diameter  of  the  threads 
be  formed.     A  piston,  which  should  fit  as  accurately 
as  possible  in  the  cylinder,  slowly  forces  the  plastic 
mass  out  of  the  above-mentioned  tubes. 

The  threads  thus  formed,  on  coming  from  the 
tubes,  first  reach  an  endless  band  of  cotton  velvet 
about  13  feet  long.  While  they  are  carried  away 
by  this  band  they  lose  a  considerable  part  of  the 
carbon  disulphide  by  evaporation,  and  obtain 
thereby  a  certain  degree  of  solidity.  From  the 
velvet  band  they  pass  to  a  second  endless  band  of 
fine  wire  gauze  which  is  kept  in  a  shaking  motion, 
while  finely  powdered  talc  falls  constantly  upon 
the  threads.  By  the  shaking  motion  of  the  band, 
the  threads  are  covered  everywhere  with  the  talc 
powder,  which  prevents  them  from  sticking  together. 

To  entirely  evaporate  the  carbon  disulphide 
which  may  still  adhere  to  them,  Aubert  and  Gerard 
use  a  system  of  endless  linen  bands  consisting  of 
five  bands,  each  about  52  feet  long.  They  are 
arranged  one  above  the  other  and  move  in  opposite 
directions  so  that  the  threads  run  to  and  fro. 

About  ten  minutes  are  required  for  them  to  run 
over  all  the  endless  bands,  and  during  this  time 
they  lose  sufficient  of  the  carbon  disulphide  that 
they  can  be  wound  upon  reels  without  sticking 
together. 

They  are  wound  in  the  same  manner  as  the  loose 
cotton  bands  in  cotton  mills.  Funnels  stand  over 
vertical  tin  boxes  which  all  revolve  around  their 


ARTICLES    FROM    SOFT    RUBBER.  179 

axes  at  the  same  velocity.  The  thread  glides 
through  the  funnels  into  the  boxes  and  is  wound 
up  in  it  to  a  spiral. 

When  the  cylinder  from  which  the  plastic  rubber 
is  forced  is  nearly  empty,  it  is  filled  up  again,  and 
in  this  manner  threads  of  any  desired  length  can 
be  manufactured.  If  threads  of  a  specific  diameter 
are  to  be  prepared,  the  fact  must  be  taken  into  con- 
sideration that  the  diameter  of  the  threads  de- 
creases considerably  in  drying.  A  thread  pressed 
through  a  tube  having  a  diameter  of  0.039  inch, 
when  dry  will  have  a  diameter  of  only  0.028  inch. 

Only  threads  having  at  least  the  diameter  men- 
tioned above  can  be  prepared  by  pressing.  If  holes 
of  a  smaller  diameter  than  0.039  inch  are  used,  the 
plastic  mass  breaks  constantly  and  the  work  cannot 
be  carried  on  without  interruption.  A  peculiar 
physical  behavior  of  rubber  is  taken  advantage  of 
for  preparing  still  thinner  threads. 

Namely,  if  a  thread  of  rubber  is  stretched  length- 
wise and  simultaneously  exposed  to  a  temperature 
of  239°  F.,  it  will  retain  the  length  to  which  it  has 
been  stretched  even  after  the  tension  ceases.  If  the 
thread  which  has  been  dried  in  this  manner  is 
again  drawn  out  lengthwise,  and  again  heated  to 
239°  F.,  it  remains  stretched,  and  by  several  times 
repeating  this  operation  threads  of  a  much  smaller 
diameter  can  be  obtained  than  is  possible  by  cutting 
or  pressing. 

Rubber  hose.  This  forms  a  very  important  com- 
mercial article,  as  on  account  of  its  pliability  and 


180    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

resistance  to  chemical  agents,  it  is  used  in  many 
industries.  The  demands  made  in  practice  on 
rubber  hose  are  manifold,  and  frequently  it  is  not 
easy  to  come  up  to  them. 

Hose  or  tubing  for  chemists'  use  and  for  conduct- 
ing illuminating  gas  should  be  as  thin  and  pliable 
as  possible,  and  at  the  same  time  impermeable  to 
gas.  Hose  for  conducting  compressed  air,  an  in- 
dispensable component  of  rock  drills,  should  be 
able  to  withstand  a  pressure  of  several  atmospheres. 

It  is  absolutely  necessary  that  hose  which  shall 
answer  all  reasonable  demands  should  not  kink 
when  used  in  short  bends.  Such  kinking  is  very 
annoying,  as  it  obstructs  the  flow  of  the  fluid  or 
gas  contained  in  the  hose  until  it  is  again  straight- 
ened out,  and  subjects  the  manufacturer  to  the 
charge  of  furnishing  unserviceable  goods.  This 
defect  is  found  chiefly  in  hose  the  walls  of  which 
are  too  thin,  and  can  be  avoided  by  maintaining 
due  proportion  between  the  diameter  and  the  walls 
of  the  hose. 

Manufacture  of  ordinary  rubber  hose.  It  is  now 
customary  to  manufacture  hose  from  vulcanized 
rubber,  it  being  more  servicable  than  that  from 
ordinary  rubber,  which  soon  becomes  brittle  and 
full  of  cracks,  especially  when  frequently  exposed 
to  changes  of  temperature. 

A  plastic  mass,  obtained  by  mechanically  treat- 
ing a  compound  of  rubber  and  sulphur,  is  used  for 
making  hose.  The  mass  is  first  rolled  into  sheets 
of  a  thickness  corresponding  with  that  of  the  walls 


ARTICLES    FROM    SOFT    RUBBER.  181 

of  the  hose  which  is  to  be  prepared,  the  interior 
diameter  of  the  latter  being  determined  by  an  iron 
core  over  which  the  plastic  mass  is  shaped. 

Cores  of  round  smooth  wire  are  generally  used 
for  hose  of  a  small  diameter,  but  for  hose  of  a  larger 
diameter  wooden  cores  are  preferred,  since  iron 
cores,  on  account  of  their  weight,  are  difficult  to 
handle.  But  the  wooden  cores  must  be  perfectly 
cylindrical,  and  it  is  advisable  to  saturate  them, 
before  use,  with  hot  linseed  oil. 

For  manufacturing  short  tubing  the  plastic  mass 
is  cut  into  bands  somewhat  wider  than  the  circum- 
ference of  the  core.  These  bands  are  then  placed 
around  the  core  and  joined  together  by  gentle 
pressure.  Finally  the  core  with  its  envelope  of  rub- 
ber is  rolled  upon  a  smooth  table  to  give  the  tubing 
a  perfectly  cylindrical  form.  It  is  then  wrapped 
in  a  linen  cloth  which  remains  around  it  during 
vulcanizing.  When  taken  from  the  heater,  the 
core  is  withdrawn,  and  the  linen  cloth  removed 
from  the  tubing,  which  is  now  finished. 

If  hose  of  greater  length  or  larger  diameter  is  to 
be  manufactured,  the  rubber  is  generally  used  in 
the  form  of  a  band,  wrhich  is  laid  in  spirals  around 
the  core  in  such  a  manner  that  the  edges  slightly 
overlap.  By  pressing  with  the  fingers  and  rolling 
upon  the  table,  they  are  joined  together  to  a  hose 
which  is  treated  in  the  same  manner  as  has  been 
described. 

But  rubber  alone  is  not  sufficient  where  the  hose 
lias  to  bear  a  great  pressure,  and  it  becomes  neces- 


182    INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

sary  to  strengthen  it  by  intermediate  layers  of 
tissues  and  spirals.  Of  course  this  increases  the 
solidity,  but  decreases  the  flexibility  of  the  hose  to 
a  great  degree. 

Rubber  hose  with  intermediate  layers  or  stiffeners. 
Hose  with  an  intermediate  layer  of  tissue  is  pre- 
pared by  first  forming  a  thin  hose  from  plastic  com- 
pound. A  piece  of  the  tissue  is  placed  over  this, 
but  this  must  be  wide  enough  to  allow  the  ends  to 
lap  over.  The  tissue  before  it  is  laid  upon  the  hose 
is  brushed  over  with  a  solution  of  rubber,  and  in 
placing  it  in  position,  great  care  must  be  observed 
to  prevent  the  formation  of  air  bubbles,  as  on  the 
places  where  such  are  present,  the  rubber  and  tissue 
do  not  unite,  and  experience  has  shown  that,  when 
the  hose  is  subjected  to  a  high  pressure,  it  bursts 
first  at  those  defective  places. 

When  the  tissue  has  been  applied,  it  is  covered 
with  a  second  layer  of  plastic  compound,  so  that  it 
is  entirely  inclosed  and  can  only  be  seen  on  the 
cross-section. 

For  hose  with  layers  of  wire,  the  latter  is  used  in 
the  form  of  spirals,  which  are  wound  over  the  hose 
formed  on  the  core,  and  then  covered  in  the  usual 
manner  with  a  second  layer  of  rubber. 

Small  hose  can  also  be  manufactured  with  the 
machine  used  for  pressing  threads.  But  in  this 
case  the  cylindrical  holes  through  which  the  plastic 
rubber  is  forced  are  replaced  by  openings  in  which 
cores  of  suitable  size  are  inserted.  The  latter  arc 
hollow,  and  are  connected  with  a  vessel  containing 


ARTICLES    FROM    SOFT    RUBBER.  183 

water.  The  small  hose  as  it  comes  from  the  cylinder 
is  closed  by  pressing  the  ends  together,  and  filled 
with  water  as  quickly  as  it  is  formed.  This  is  abso- 
lutely necessary,  as  the  hose  would  collapse  if  this 
precaution  were  neglected,  and  the  sides  stick 
together.  The  subsequent  treatment  of  the  hose  is 
exactly  the  same  as  that  of  the  threads.  When  it  is 
finished,  it  is  opened  and  the  water  allowed  to  escape. 

Tubing  machines  of  various  sizes  are  manufac- 
tured by  John  Royle  and  Sons,  of  Paterson,  N.  J. 
Fig.  11  shows  their  tubing  machine  No.  2,  which  is 
well  adapted  to  making  the  larger  sizes  of  tubing, 
such  as  fire-hose  lining,  etc.,  and  for  making  various 
shapes  of  a  greater  size  than  can  be  conveniently 
handled  in  smaller  machines,  which  are  more  suit- 
able for  syringe  and  flower  tubing  and  various 
small-sized  druggists'  and  stationers'  sundries. 

The  most  important  feature  of  a  tubing  machine 
is  the  cylinder,  upon  the  construction  of  which  the 
harmonious  working  of  the  various  parts  depends, 
as  it  is  in  the  cylinder  that  the  heat  necessary  for 
the  proper  working  of  the  compound  is  applied. 
Nearly  all  the  different  tubing  compounds  are 
highly  sensitive  to  the  action  of  heat,  and  require 
to  be  subjected  to  various  degrees  of  temperature  at 
different  points  while  passing  through  the  machine. 
To  produce  the  heat  in  sufficient  quantities,  and 
under  perfect  control  as  to  direction  and  extent,  has 
been  the  main  object  aimed  at  in  the  construction 
of  the  cylinder  in  the  Royle  machines.  Thus  when 
working  india  rubber  or  other  similar  material,  it 


184    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

is  necessary  to  heat  the  head  and  cylinder  so  as  to 
soften  the  mass  and  facilitate  its  delivery  through 
the  die,  and  it  is  also  essential  that  the  degree  of 
heat  applied  should  be  readily  controllable  in  order 
FIG.  11. 


that  the  consistency  of  the  material  may  be  so  regu- 
lated that  it  will  become  sufficiently  plastic  to  mold 
readily,  and  at  the  same  time  retain  the  form  given 
to  it  by  the  die.  To  effect  this  result  it  may  be 


ARTICLES    FROM    SOFT    RUBBER.  185 

necessary,  in  some  cases,  to  heat  both  the  cylinder 
and  the  head,  while  in  others  it  may  be  necessary  to 
heat  only  the  cylinder  and  cool  the  head,  or  to  cool 
both  cylinder  and  head.  To  provide  for  all  con- 
tingencies, both  head  and  cylinder  are  jacketed,  and 
equipped  with  a  steam-chest  having  separate  com- 
partments for  steam  and  hot  water.  Suitable  pas- 
sages issue  from  these  compartments  for  conveying 
the  steam  and  water  directly  to  the  cylinder  and 
head,  and  an  arrangement  of  valves  is  provided,  by 
means  of  which  the  flow  of  water  and  steam  can  be 
regulated,  and  any  desired  temperature  maintained. 
The  passages  and  valves  are  arranged  as  integral 
parts  of  the  machine,  and  no  external  pipes  or  con- 
nections are  needed,  except  the  main  supply  and 
discharge  pipes  for  conducting  the  heating  and 
cooling  fluids  to  and  from  the  valve-chest.  The 
bore  of  the  cylinder  has  a  suitable  lining,  so 
arranged  that,  in  the  event  of  wear,  it  can  be 
replaced  at  a  nominal  cost. 

The  head  for  holding  the  dies,  etc.,  for  giving  the 
desired  form  to  the  material  as  it  issues  from  the 
machine,  is  so  arranged  that  dies,  cores  and  core- 
bridge  can  be  readily  removed  from  the  front  of  the 
machine  without  disturbing  it.  It  can,  however,  be 
readily  detached,  when  desired,  by  simply  loosen- 
ing the  nuts  on  the  stud-bolts  by  which  it  is  attached 
to  the  cylinder. 

The  dies  which  give  form  to  the  outside  of  the 
compound  as  it  issues  from  the  machine  are  made 
in  two  styles,  thimble  and  thread,  and  are  hel< 


186    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

place  in  the  machine  by  means  of  holders  which 
screw  into  the  head  from  the  front.  The  thimble 
dies  are  fitted  into  the  bore  of  the  holder  from  the 
back  and  are  held  in  place  by  a  rim  of  metal,  while 
the  threaded  dies  are  hexagonal-shaped  on  the  out- 
side and  have  a  threaded  stem  which  screws  into 
the  holder  from  the  front.  The  holders  for  both 
styles  of  dies  are  graduated  in  size,  so  that  each 
holder  will  accommodate  a  series  of  dies  of  different 
sizes.  Thus,  with  very  few  holders,  a  large  assort- 
ment of  dies  can  be  used. 

The  cores  used  in  making  tubing  are  secured 
between  the  head  and  cylinder  by  a  core  bridge. 
As  the  core  must,  of  necessity,  be  concentric  with 
the  die  in  order  to  insure  uniform  thickness  in  the 
tubing,  an  adjusting  device  is  provided,  by  means 
of  which  the  position  of  the  core  can  be  easily 
regulated.  This  device  consists  of  four  screws 
placed  at  regular  intervals  around  the  core  bridge 
and  bearing  on  it  at  different  points  of  its  circum- 
ference. By  simply  tightening  or  loosening  these 
screws,  the  core-bridge  and  core  can  be  readily 
secured  in  any  desired  position  and  perfect  alignment 
with  the  die  maintained.  This  provision  for  main- 
taining absolute  relative  accuracy  between  the  die 
and  the  core  is  an  important  feature  of  the  machine. 
The  method  of  adjusting  from  the  core-bridge 
instead  of  from  the  core  itself,  together  with  the 
axial  adjustment  of  both  die  and  core,  renders  it 
possible  to  maintain  perfect  alignment  without 
deflecting  the  core  or  impeding  the  flow  of  the 
compound. 


ARTICLES    FROM    SOFT    RUBBER.  187 

The  rubber  or  other  raw  material  is  fed  into  the 
cylinder  through  an  opening  at  the  back,  and  is 
then  carried  along  and  forced  through  the  die  by  a 
powerful  Archimedean  screw  or  stock-worm  which 
extends  along  nearly  the  entire  length  of  the 
cylinder,  and  is  turned  by  powerful  worm  or  spur 
gearing,  as  the  case  may  be.  This  stock-worm  is 
made  of  steel,  and  is  very  durable;  the  walls  of  the 
threads  being  of  sufficient  thickness  to  withstand 
the  wear  and  tear  of  constant  use  for  an  unusually 
long  time.  As  it  is  sometimes  desirable  to  change 
the  worm  in  use  for  one  of  different  capacity,  these 
machines  are  so  arranged  that  the  stock-worm  in 
use  can  be  removed  and  another  substituted  without 
difficulty. 

A  valuable  feature  is  the  carrying  belt,  or  apron, 
for  conveying  the  tubing  or  other  product  from  the 
die.  without  stretching  or  distortion.  This  apron 
extends  from  immediately  beneath  the  die  to  a  re- 
volving pan,  or  other  appropriate  receptacle,  placed 
on  the  floor  at  a  suitable  distance  from  the  machine. 
It  is  supported  by  an  adjustable  arm  extending  from 
the  machine,  and  the  driving  mechanism  can  be  so 
adjusted  as  to  make  the  delivery  of  the  tubing  from 
the  die  and  the  movement  of  the  apron  synchronous. 
This  receiving  apparatus  is  a  distinctive  feature  of 
the  Koyle  machines,  and  adds  materially  to  the 
quality  of  the  finished  product,  as  it  not  only  pre- 
vents distortion  and  wrinkling,  but  also  allows  the 
soft  and  impressible  gum  sufficient  time  to  harden 
somewhat  before  being  delivered  into  the  pan.  This 


188    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA.  * 

is  an  advantage  that  practical  makers  of  rubber 
goods  will  readily  understand. 

Rubber  sponge  or  moss  rubber.  This  peculiar  pro- 
duct was  first  manufactured  by  P.  W.  Cow,  Hill  & 
Co.  The  mode  of  manufacture  is  still  kept  secret, 
but  is  said  to  consist  in  repeated  vulcanization, 
softening  and  pouring  into  moulds,  the  resulting 
product  being  a  sort  of  sponge  more  or  less  cellular 
and  porous  like  a  sponge,  and  possessing  the  prop- 
erty of  absorbing  water  and  allowing  it  to  escape 
when  pressed.  Dr.  Wiederhold  is  of  the  opinion 
that  rubber  sponge  is  prepared  as  follows :  A  solu- 
tion of  rubber  in  carbon  disulphide,  or  chloroform, 
or  benzene,  is  quickly  heated,  whereby  the  last 
remnants  of  the  solvent  distend  the  mass,  which  has 
become  very  viscous,  and  thus  imitate  the  cellular 
structure  of  sponge. 

According  to  other  experiments,  rubber  sponge 
may  be  produced  as  follows  :  A  tall  tin  vessel  of 
prismatic  shape  is  filled  a  fewT  centimeters  deep 
with  rubber  solution  and  the  latter  heated  to  above 
the  boiling-point  of  the  solvent  used  in  the  prepara- 
tion of  the  solution.  In  consequence  of  the  evap- 
oration of  the  solvent,  the  mass  becomes  more  and 
more  viscous,  and  as  the  steam  bubbles  force  their 
way  through  it  with  constantly  increasing  diffi- 
culty, the  final  result  is  a  very  porous  and  cellular 
product.  By  using  rubber  dough  and  heating  very 
slowly,  sponge  with  very  fine  pores  is  obtained 
which  as  regards  softness,  by  far  surpasses  the 
finest  bathing  sponge.  The  finished  product  is 


ARTICLES    FROM    SOFT    RUBBER.  189 

vulcanized  by  plunging  it  into  a  solution  of  chloride 
of  sulphur,  and  may  be  further  provided  with  a 
suitable  base  of  hard  rubber  so  as  to  make  it  handy 
for  use. 

However,  the  disagreeable  odor  of  these  sponges, 
which  is  perhaps  more  perceptible  on  account  of 
their  porous  nature  than  is  the  case  with  other  vul- 
canized rubber  articles,  prevents  their  general  use. 
This  odor  can,  however,  to  some  extent,  be  over- 
come by  the  use  of  animal  charcoal.  The  sponges 
are  simply  wrapped  up  in  tissue  paper  and  placed 
in  a  vessel  filled  with  powdered  animal  charcoal. 
In  a  few  weeks,  especially  if  the  vessel  be  put  in 
a  warm  place,  the  sponges  will  have  lost  nearly  all 
odor,  and  the  last  traces  of  it  may  be  removed  by 
washing.- 

These  rubber  sponges  have  been  highly  recom- 
mended for  washing  horses,  they  having  the  ad- 
vantage over  the  curry-comb  of  not  injuring  the 
skin  of  the  animal  or  tearing  out  hair,  while  at 
the  same  time  the  dust  is  completely  removed  and 
a  beautiful  lustre  is  imparted  to  the  hair.  In  the 
form  of  brushes,  provided  with  a  hard  rubber  back, 
they  have  been  recommended  for  cleaning  clothes, 
cloth,  ribbons,  fine  tissues,  such  as  velvet,  etc. 

Rubber  shoes.  In  the  course  of  time  this  article 
has  passed  through  a  peculiar  process  of  develop- 
ment. The  first  so-called  gum  shoes  consisted  of  a 
single  piece  of  rubber  and  were  made  in  the  same 
manner  as  the  bottles  of  crude  rubber.  Clay 
moulds  in  the  shape  of  a  last  were  coated  with  the 


190        INDIA    RUBBER,  GUTTA    PRRCHA,  BALATA. 

latex  and  dried  over  a  fire.  The  congealed  coating 
was  then  drawn  from  the  last  and  formed  the  shoe. 
Shoes  prepared  in  this  manner  were  very  durable, 
but  ugly,  and  had  the  further  defect  of  enclosing  the 
feet  tightly  and  producing  in  them  in  a  short  time 
a  feeling  of  almost  unbearable  heat.  Later  on 
shoes  were  made  by  cementing  together  pieces  of 
rubber,  but  these  had  the  defect  of  soon  losing  their 
elasticity.  Goodyear  was  the  first  to  make  shoes  of 
vulcanized  rubber,  and  the  extent  of  the  present 
manufacture  may  be  judged  from  the  fact  that  a 
single  factory  turns  out  3000  pairs  a  day.  It  may, 
however,  be  mentioned  here  that  under  the  name 
of  rubber  shoes,  products  are  brought  into  the 
market  which  do  not  deserve  the  name,  as  no 
rubber  whatever  is  used  in  their  manufacture,  but 
only  elastic  varnish  colored  black. 

Genuine  rubber  shoes  are  made  as  follows :  A 
tricot-like  tissue  is  coated  by  passing  through  be- 
tween rolls  with  a  thin  layer  of  sulphurized  rubber 
colored  black  with  lamp-black.  The  separate  parts 
which  are  to  form  the  shoe  are  cut  from  the  sheet 
thus  prepared,  the  sole  being  cut  from  a  somewhat 
thicker  sheet,  and  cemented  together  with  rubber 
solution  over  hollow  iron  lasts.  They  are 'then 
coated  with  asphalt  lacquer  and  vulcanized  over 
.the  last. 

Bicycle  tires.  Pneumatic  tires  for  bicycles,  etc., 
may  be  divided  into  two  classes :  Single-tube  tires, 
in  which  an  endless  tube  is  made  air-tight  and 
sufficiently  strong  to  resist  the  air  pressure,  and 


ARTICLES    FROM    SOFT    RUBBER.  191 

compound  tires  consisting  of  two  parts — an  inner 
air  tube  and  an  outer  cover. 

Single  tube  tires  are  formed  of  alternate  layers  of 
more  or  less  pure  rubber  and  strong  cloth  or 
canvas.  The  interior  is  made  of  pure  or  nearly 
pure  rubber,  the  object  of  its  introduction  being  to 
form  an  absolutely  impervious  surface  to  the  pas- 
sage of  air.  The  strength  of  this  inner  layer  is 
practically  nothing,  its  principal  office  being  to  fill 
the  interstices  found  in  the  material  surrounding  it, 
and  which  possesses  the  necessaiy  strength  to  resist 
the  inflation  by  the  air. 

Mr.  Henry  Sturmey  divides  compound  tires  into 
five  classes  according  to  the  mode  of  adjustment  of 
the  outer  cover  to  the  rim,  viz  :  Solutioned  tires, 
wrired  tires,  interlocking  and  inflation-held  tires, 
laced  tires  and  band-held  tires.  It  would  lead  too 
far  to  describe  all  these  classes  of  tires,  and  hence 
only  a  description  of  the  original  "  Dunlop  "  tire, 
with  which  originated  the  principle  of  air  tubes 
for  cycles,  will  be  given,  and  of  the  Morgan  and 
Wright  tire,  both  of  which  belong  to  the  solu- 
tioned  type  of  tires.  In  the  Dunlop  tire  the  outer 
cover  consists  of  a  thick  tread  of  rubber  solutioned 
to  a  canvas  strip.  A  complete  woven  tube  of  canvas 
encircles  the  air  tube  and  is  solutioned  to  the  rim, 
which  is  previously  wrapped  round  by  a  canvas 
strip,  while  the  flaps  of  the  outer  cover  are  solu- 
tioned to  the  inner  surface  of  the  rim,  one  flap 
being  hipped  over  the  other,  the  side  being  split  to 
pass  the  spokes.  A  strip  of  canvas  solutioned  over 
the  flaps,  makes  a  neat  finish. 


192    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

In  the  Morgan  and  Wright  type,  the  air-tube  is 
butt-ended,  or  rather  scarf-ended,  the  two  ends  over- 
lapping each  other  about  eight  or  ten  inches.  The 
outer  covers  form  practically  a  tube  slit  for  a  few 
inches  along  its  under  side.  This  opening  serves 
for  the  insertion  of  the  air-tube,  and  is  laced  up 
when  the  air-tube  is  in  place.  When  partially  in- 
flated the  tire  is  cemented  on  the  rim. 

Manufacture  of  water-proof  tissues.  There  are  two 
kinds  of  water-proof  tissues,  known  as  double  text- 
ures and  single  textures.  The  first  consist  of  two 
layers  of  the  same  or  different  stuffs  cemented  to- 
gether by  a  thin  layer  of  rubber.  Single  textures 
consist  of  a  single  tissue  which  is  coated  with  rub- 
ber either  only  on  one  side  (single  face)  or  on  both 
sides  (double  face). 

Rubber  was  first  used  in  the  manufacture  of 
water-proof  tissues  by  Charles  Macintosh,  and  the 
material  was  called  by  the  name  of  the  inventor. 
It  possessed  the  advantage  of  being  very  durable, 
but  on  the  other  hand  had  the  disadvantage  of 
being  very  weighty,  thick  and  expensive.  It  was 
prepared  by  placing  a  thin  sheet  of  rubber  between 
two  tissues  and  passing  the  whole  through  between 
heated  rolls. 

By  this  manipulation  the  rubber  was  so  strongly 
heated  that  it  became  soft,  and  was  pressed  into  the 
meshes  of  the  fabrics,  cementing  them  firmly  to- 
gether. Many  experiments  were  made  to  improve 
Macintosh's  process  by  decreasing  the  weight  and 
thickness  of  the  materials,  but  this  has  only  been 


ARTICLES    FROM    SOFT    RUBBER.  193 

accomplished  since  the  introduction  of  the  new  pro- 
cess of  working  rubber,  which  renders  possible  the 
preparation  of  very  thin  sheets. 

Dumas  suggested  the  preparation  of  very  thin 
sheets  by  allowing  a  solution  of  rubber  in  ether  to 
run  down  over  heated  rolls.  The  ether  would 
thereby  evaporate  and  the  soft  thin  sheet  remaining 
behind,  which  could  readily  be  detached  from  the 
polished  rolls,  was  to  be  spread  upon  the  tissue. 
The  latter  was  to  be  covered  with  a  second  layer  01 
tissue  and  the  whole  cemented  together  by  rolling. 

It  is  absolutely  necessary  that  the  layer  of  rubber 
should  be  as  thin  as  possible,  if  it  is  desired  to  pre- 
pare an  article  which  will  answer  all  reasonable 
demands.  So  much  progress  has  been  made  in 
cutting  cylinders  of  rubber  into  thin  sheets,  that 
they  can  be  furnished  not  much  thicker  than  a 
sheet  of  writing  paper.  A  successful  attempt  has 
been  made  to  coat  only  one  side  of  a  tissue  with 
such  thin  sheets,  but  this  unfortunately  has  the 
disadvantage  of  making  the  material  heavy,  and  of 
being  rather  expensive.  A  decided  improvement 
in  the  manufacture  of  water-proof  materials  has 
only  been  made  since  the  process  of  obtaining  rub- 
ber in  a  very  soft  form  by  mechanical  treatment 
became  known,  but  the  greatest  perfection  in  the 
manufacture  of  this  important  article  has  only  been 
reached  since  the  introduction  of  vulcanized  rubber. 

The  first  improvement  in  Mackintosh's  process 
consisted  in  the  use  of  but  one  layer  of  tissue,  and 
by  making  the  sheet  of  rubber  as  thin  as  possible, 
13  ^ 


194    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

the  bulk  of  the  material  was  considerably  decreased. 
The  manner  of  manufacturing  these  water-proof 
fabrics  was  very  simple,  and  was  carried  on  as  fol- 
lows : 

The  crude  rubber  was  first  converted  into  as 
homogeneous  a  mass  as  possible  by  passing  it 
through  between  rolls,  and  was  finally  rolled  into 
very  thin  sheets.  When  the  latter  are  "taken  from 
the  rolls  they  are  quite  sticky,  and  this  is  made  use 
of  for  cementing  them  to  the  tissue,  which  is  ac- 
complished by  placing  the  fabric  upon  the  sheet- 
of  rubber  and  passing  the  whole  through  between 
rolls. 

Before  entering  upon  the  discussion  of  the  more 
modern  methods  of  making  water-proof  fabrics,  a 
few  words  may  be  said  about  the  character  of  the 
tissues  to  be  employed.  The  material  may  be 
either  silk,  wool  or  cotton  ;  as  the  tissue  is  simply 
the  bearer  of  the  substance  which  renders  it  water- 
proof, either  loosely  or  closely  woven  fabrics  may 
be  used.  In  the  first  case  a  considerable  quantity 
of  rubber  is  required  for  water-proofing,  and  in  the 
latter  only  a  small  quantity. 

Most  manufacturers  have  found  it  best  to  use 
closely  woven  fabrics  for  water-proof  tissues,  as 
these  require  less  rubber  and  besides  have  the 
advantage  of  being  firmer.  Therefore  strong  cotton 
goods  are  generally  used  at  the  present  time  for 
finer  articles,  such  as  water-proof  coats  and  cloaks. 
The  principal  requisite  of  such  materials  is  that 
they  should  be  as  even  and  smooth  as  possible,  since 


ARTICLES    FROM    SOFT    RUBBER.  195 

even  the  smallest  knot  in  the  tissue  exerts  an  in- 
jurious effect  upon  the  quality  of  the  goods  to  be 
manufactured. 

At  the  present  time,  as  has  been  mentioned,  very 
thin  coatings  of  rubber  can  be  prepared.  If  there 
should  be  knots  in  the  tissue  they  would,  of  course, 
be  covered  with  rubber  and  the  fabric  would  seem 
to  be  of  excellent  quality  as  long  as  it  is  not  used. 
But,  if  a  garment  made  of  such  material  is  used 
for  a  short  time,  the  rubber  will  commence  to  peel 
'off  wherever  the  knots  are. 

Fabrics  of  cloth  and  vulcanized  rubber  can  be 
prepared  by  rolling  the  soft  compound  of  rubber 
and  sulphur  into  very  thin  sheets  and  passing  them 
together  with  the  cloth  through  between  heated 
rolls.  The  object  of  heated  rolls  is  to  force  the 
rubber  compound  firmly  into  the  meshes  of  the 
tissue,  and,  if  the  proper  temperature  be  used,  at 
the  same  time  to  vulcanize  the  rubber. 

One  pair  of  rolls,  heated  to  the  temperature  re- 
quired for  vulcanizing,  may  suffice  for  the  work, 
but  very  careful  arid  skilled  workmen  are  then  re- 
quired. Experience  has  shown  that  it  is  much 
better  to  use  two  pairs  of  rolls,  the  first  pair  of 
which  is  heated  at  the  utmost  to  248°  F.,  while  the 
second  is  heated  to  the  temperature  required  for 
vulcanizing  the  rubber  compound.  Finally,  the 
finished  fabric  is  rolled  upon  cylinders  as  soon  as  it 
has  become  sufficiently  cooled  off,  and  should  be 
further  worked  as  soon  as  possible. 

It  is,  however,  difficult  to  obtain  uniform  pro- 


196   INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

ducts  in  this  manner,  and  experiments  have,  there- 
fore, been  made  to  use  vulcanized  rubber.  But  as 
this,  as  is  well  known,  cannot  be  cemented  to- 
gether, and  will  not  combine  with  the  tissues  by 
pressing,  it  is  necessary  to  have  recourse  to  certain 
manipulations  to  obtain  the  desired  object. 

According  to  the  method  recommended  by  John- 
son, very  thin  sheets  of  vulcanized  rubber  are  pre- 
pared, and  these  partly  desulphurized  by  boiling 
for  some  time  in  caustic  soda.  After  they  have 
been  boiled,  they  are  first  washed  in  water  contain- 
ing some  hydrochloric  acid  (to  remove  the  last 
traces  of  the  alkali),  next  in  pure  water,  and  then 
dried. 

The  sheets,  thus  prepared,  are  roughened  by 
passing  them  over  a  roll  covered  with  emery  paper 
and  revolving  with  great  speed  (800  to  900  revolu- 
tions a  minute).  The  object  of  this  is  to  facilitate 
the  union  of  the  rubber  with  the  tissue. 

The  sheet  is  then  coated  with  a  rubber  solution 
and  placed  upon  the  tissue  and  both  together  are 
passed  through  between  the  rolls  in  order  to  cement 
them  together. 

The  articles  manufactured  in  this  manner  are  of 
excellent  quality,  but,  on  account  of  the  process 
being  so  very  complicated,  rather  expensive.  Since 
the  method  of  completely  dissolving  rubber  has 
become  known,  solutions,  or  a  paste  of  it,  are  almost 
exclusively  used  for  the  manufacture  of  water-proof 
tissues,  and  these  are  generally  only  coated  on  one 
side. 


ARTICLES    FROM    SOFT    RUBBER.  197 

Although  the  work  seems  to  be  very  simple  when 
solutions  are  used,  nevertheless  many  difficulties 
present  themselves  in  the  execution  of  the  operation. 
Frequently  the  very  volatile  oils,  which  are  ob- 
tained by  distilling  coal  tar — light  coal-tar  oil  or 
naphtha — are  used  as  solvents  on  account  of  their 
cheapness.  It  is  true  that  these  solvents  volatilize 
very  quickly,  but  they  are  mostly  always  mixed 
with  small  quantities  of  less  volatile  products, 
which  remain  behind  after  the  volatilization  of  the 
lighter  oils,  and  the  odor  of  which  adheres  to  the 
rubber  so  that  it  is  perceptible  for  years.  This  odor 
— agreeable  to  no  one — is  so  repulsive  to  some  per- 
sons that  they  will  not  use  a  garment  manufactured 
from  such  tissue. 

A  further  evil  of  using  pure  rubber  solutions  is 
that  the  layer  of  rubber,  which  is  left  behind,  re- 
mains sticky  for  some  time,  and,  for  this  reason,  a 
garment,  prepared  from  it,  cannot  be  folded  up,  as 
the  surfaces  would  stick  together  so  tight  that  the 
folds  could  not  be  separated. 

All  these  evils  are  now  removed  by  using  a  rub- 
ber paste  which  also  contains  the  substance  re- 
quired for  vulcanization,  and  by  subjecting  the 
freshly  coated  tissue  to  the  heating  process. 

Such  solutions,  or  more  correctly  speaking,  such 
compounds,  used  for  this  purpose  are  at  once  mixed 
with  the  quantity  of  sulphur  required  for  vulcaniza- 
tion. The  simplest  manner  of  doing  this  is  to  sat- 
urate the  carbon  disulphide  used  for  dissolving  the 
rubber  with  sulphur,  or  by  working  very  finely 


198    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

powdered  sulphur  into  the  mass.  The  principal 
requisite  for  a  correct  execution  of  the  work  is,  that 
the  mass  should  be  entirely  homogeneous,  a  prop- 
erty which  can  be  imparted  to  it  by  a  suitable 
mechanical  treatment,  as  has  been  explained  in  a 
previous  chapter. 

For  spreading  the  rubber  compound  upon  the 
tissue  as  uniformly  as  possible  and  to  cement  both 
together,  a  special  machine  is  required.  It  makes 

FIG.  12. 


very  little  difference  which  of  the  various  makes  of 
machine  is  used,  as  they  all  answer  the  purpose  for 
which  they  are  intended,  a  thoroughly  experienced 
workman  being  the  principal  requisite  for  the  work. 

A  spreader  well  adapted  for  all  purposes  is 
shown  in  Fig.  12. 

Two  rolls  of  small  diameter,  generally  7  to  7{ 
inches,  rest  in  brasses  upon  a  suitable  frame.  The 


ARTICLES    FROM    SOFT    RUBBER.  199 

lower  roll  is  made  to  revolve  and  is  set  in  motion 
by  cog-wheels  and  the  crank  K,  with  which  they 
are  connected.  The  upper  roll  has  square  arbors 
which  fit  into  the  brasses,  and  therefore  it  does  not 
revolve. 

The  object  of  the  upper  roll  is  to  regulate  the 
thickness  of  the  solution  which  is  to  be  spread 
upon  the  tissue,  and  for  this  purpose  is  provided 
with  a  peculiar  mechanism.  Two  levers,  H,  H, 
having  their  fulcrum  at  b,  and  loaded  with  weights 
G,  press  with  a  certain  force  the  upper  roller 
against  the  lo.wer  one,  this  force  increasing  in 
power  the  more  horizontal  the  position  of  the 
levers  becomes. 

As  may  be.  seen  in  the  accompanying  illustration 
the  levers  are  double-armed,  and  on  the  other  end 
are  connected  with  chains,  which  can  be  wound 
upon  pulleys.  The  less  the  pressure  shall  be, 
which  is  to  be  exerted  upon  the  upper  roller,  that 
is  to  say,  the  thicker  the  rubber  compound  is  to  be 
spread  upon  the  tissue,  the  tighter  the  chains  are 
drawn,  and  the  more  the  arm  of  the  lever,  pro- 
vided with  weights,  is  raised. 

The  tissues  to  be  converted  into  water-proof  fab- 
rics are  wrapped  around  a  roller,  and  are  wound 
upon  a  cylinder  after  they  have  been  provided  with 
the  solution,  and  sufficiently  dried,  so  that  the  sep- 
arate folds  will  not  stick  together. 

As  has  previously  been  mentioned,  the  more 
closely  woven  the  fabric  is,  the  thinner  the  rubber 
compound  can  be  spread  upon  it,  and  there  is  no 


200    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

danger  of  soaking  through,  which  must  by  all 
means  be  avoided.  For  tissues  with  a  looser  text- 
ure, a  rubber  compound  of  greater  consistency  has 
to  be  employed,  as  thin  solutions  would  soak 
through. 

The  thinner  the  rubber  compound  is,  the  more 
beautiful  and  uniform  the  coating  will  be,  and  for 
this  reason  it  is  necessary  to  apply  several  coatings 
to  the  tissue  to  render  it  entirely  water-proof.  For 
the  first  coat  the  compound  should  be  of  sufficient 
consistency  to  prevent  all  danger  of  soaking 
through.  In  many  factories  the  solution  or  com- 
pound is  still  applied  by  means  of  ladles,  which  a 
workman  fills  from  a  vessel  containing  the  material. 

As  the  tissue  advances  between  the  rolls,  he  pours 
the  solution  upon  it,  and  it  will  be  readily  under- 
stood that  considerable  skill  is  required  to  pour  the 
solution  in  such  a  manner  as  to  spread  exactly  the 
right  quantity.  And,  as  besides  the  solutions 
always  contain  fluids,  the  vapors  of  which  exert  an 
injurious  effect  upon  the  health  of  the  workmen, 
the  manufacture  of  water-proof  tissues  in  this  primi- 
tive manner  deserves  to  be  called  very  unhealthy 
work. 

To  protect  the  workmen  from  the  evil  effects  of 
the  vapors,  the  tissue,  after  it  has  been  coated,  is 
brought  into  a  room  from  which  the  vapors  are 
constantly  pumped. 

But  this  gives  only  temporary  protection,  as  the 
workman  who  ladles  the  fluid  from  the  vessel  and 
spreads  it  upon  the  tissue,  to  be  sure,  does  not  suffer 


ARTICLES  FROM  SOFT  RUBBER.        201 

from  the  vapors  which  are  formed  behind  the 
rollers,  but  is  exposed  to  those  developed  on  the 
other  side  of  the  apparatus. 

A  very  simple  contrivance,  represented  by  Fig. 
13,  may  be  used  for  removing  this  evil,  and  at  the 
same  time  for  spreading  the  mass  as  uniformly  as 
possible  upon  the  tissue.  This  apparatus  consists 
of  a  sheet-iron  box  K,  having  the  shape  of  a  three- 
sided  prism,  which  serves  for  the  reception  of  the 
solution  or  compound.  The  box  is  placed  imme- 

FIG.  13. 


diately  behind  the  rolls  W.  The  lid  of  the  box 
catches  into  a  gutter  filled  with  water,  which  pre- 
vents the  escape  of  vapors  into  the  workroom. 

A  cock,  H,  is  fitted  into  the  lid,  which  is  only 
opened  at  the  commencement  of  the  operation,  and 
allows  air  to  enter  into  the  interior  of  the  box  as 
soon  as  the  contents  commence  to  run  off.  On  the 
lower  edge  of  the  box  is  a  slide  which  closes  a  slit 
in  the  box  through  which  the  fluid  escapes. 

Close  to  the  rolls  stands  a  sheet-iron  case,  G,  hav- 
ing the  form  of  a  house  with  a  steep  roof.  It  is 


202    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

somewhat  wider  than  the  tissue  which  slides  along 
upon  the  bottom  of  it,  and  passes  out  through  as 
narrow  an  opening  as  possible.  On  top  of  the  roof 
is  a  pipe,  R,  provided  all  around  with  fine  holes, 
and  connected  with  a  reservoir  constantly  filled 
with  cold  water.  On  the  sides  of  the  box  are 
several  pipes  for  carrying  off  the  fluid  dripping 
down. 

The  apparatus  works  as  follows : 

A  stream  of  the  solution  as  wide  as  the  tissue  to 
be  coated  flows  through  the  slit  in  the  vessel,  which 
has  been  opened  just  as  wide  as  it  is  necessary,  the 
rolls  spreading  it  upon  the  tissue  in  an  entirely 
uniform  layer.  The  part  of  the  bottom  of  the  box 
nearest  to  the-  rolls,  into  which  the  tissue  passes,  is 
heated  by  hot  water  contained  in  the  pipes  S. 
Evaporation  of  the  solvent  commences  at  once,  and 
the  vapors  rise  up  to  the  roof.  But  this  is  con- 
stantly cooled  off  by  the  water  falling  down  like 
rain,  and  the  vapors,  on  coming  in  contact  with  the 
cold  surface,  are  condensed,  or  at  least  the  greater 
part  of  them,  and  run  down  on  the  inside  of  the 
box,  and  escape  from  it  through  the  discharge-pipes, 
the  fluid  being'  collected  in  flasks  placed  under 
them. 

The  best  plan  is  to  arrange  the  work  so  that  the 
manufacture  of  water-proof  tissues  can  be  carried  on 
in  the  cold  season  of  the  year.  The  rolls  and  the 
vessel  containing  the  solution  should  then  be  put  in 
a  heated  room,  while  the  sheet-iron  box,  in  which 
the  solvent  is  condensed  to  a  fluid,  is  placed  in  the 


ARTICLES    FROM    SOFT    RUBBER.  203 

open  air.  With  such  an  arrangement  the  workmen 
do  not  suffer  from  the  injurious  vapors,  the  work 
can  be  carried  on  without  interruption,  and  the 
greater  part  of  the  solvent  may  be  regained. 

As  a  certain  quantity  of  the  solvent  still  adheres 
to  fabrics  which  have  recently  been  finished,  arid 
causes  them  to  be  sticky,  it  is  advisable  not  to  wrap 
them  up  immediately  after  they  come  from  the 
apparatus,  but  to  keep  them  stretched  out  for 
several  days  as  smoothly  as  possible. 

If  tissues  for  the  manufacture  of  garments  are  to 
be  prepared,  a  certain  quantity  of  lampblack  is 
added  to  the  rubber  compound  before  its  mechan- 
ical treatment  is  commenced,  and  worked  with  it 
for  the  purpose  of  imparting  a  uniformly  black 
color  to  it. 

A  coating  of  light  brown  color  is  obtained  by 
using  rubber  in  a  pure  condition.  By  mixing  it 
with  sulphur  and  heating  the  ready  tissue  to  the 
temperature  required  for  vulcanization,  the  coating 
will  show  the  peculiar  gray  coloring  of  vulcanized 
rubber. 

Tissues  with  an  intermediate  layer  of  rubber.  Cut 
sheets  of  rubber  are  no  longer  used  for  manufactur- 
ing such  water-proof  fabrics  as  were  first  made  by 
Mackintosh,  solutions  being  now  generally  em- 
ployed for  the  purpose.  The  tissues  are  cemented 
together  with  the  assistance  of  an  apparatus  shown 
in  Fig.  14. 

The  tissues  having  been  wound  upon  the  cyl- 
inders W,  are  unrolled  in  the  direction  indicated 


204        INDIA    RUBBER,  GUTTA    PERCHA,  BALATA. 

by  the  arrows  and  pass  through  between  two  rolls 
placed  in  a  horizontal  position.  A  vessel  resem- 
bling the  one  represented  in  Fig.  13,  contains  the 
rubber  solution,  and  is  placed  exactly  over  the 
rollers.  The  solution  is  allowed  to  run  from  this 
vessel  by  opening  the  slide  in  the  bottom  of  it  as 
wide  as  may  be  necessary,  and  on  reaching  the 
tissues,  it  is  forced  into  their  meshes  by  the  rolls. 
A  second  pair  of  rolls,  placed  beneath  the  others 

FIG.  14. 


and  heated  by  steam,  effect  the  evaporation  of  the 
solvent.  The  finished  tissues  are  hung  up  for  a 
few  days  to  allow  them  to  become  completely  dry. 

Deodorizing  water-proof  fabrics.  The  odor  of  the 
solvent  adhering  for  a  long  time  to  tissues  water- 
proofed by  means  of  pure  rubber,  it  becomes  neces- 
sary to  remove  this  odor  as  much  as  possible.  Ex- 
posure to  a  higher  temperature,  even  for  a  longer 
time,  is  not  sufficient  for  the  purpose.  More  satis- 


ARTICLES    FROM   SOFT   RUBBER.  205 

factory  results  are  obtained  by  constantly  changing 
the  air  in  the  heated  chamber  in  which  the  tissues 
are  suspended,  for  instance  by  conducting  a  current 
of  hot  air  through  it. 

It  is  a  well-known  fact  that  certain  bodies  which 
volatilize  with  great  difficulty  when  left  to  them- 
selves, do  so  very  readily  when  brought  in  contact 
with  hot  steam,  and  this  process  may  be  used  for 
removing  the  disagreeable  odor  from  tissues  coated 
with  pure  rubber. 

The  simplest  plan  is  to  use  the  saturated  steam  as 
furnished  by  the  steam  boiler  of  the  factory.  The 
tissues  are  suspended  in  a  properly  arranged  room, 
and  the  steam  is  passed  into  the  latter  through  sev- 
eral openings.  A  rather  narrow  escape  pipe  for  the 
steam  is  placed  at  the  other  end  of  the  room,  and 
provision  must  be  made  for  the  escape  of  the  con- 
densed water.  A  pressure  of  but  little  more  than 
one  atmosphere  is  sufficient  for  all  purpose's,  and 
the  tissues  will  be  entirely  deodorized  after  they 
have  been  exposed  for  some  time  to  the  action  of 
the  steam.  Oil  of  turpentine  is  frequently  employed 
for  dissolving  the  rubber,  especially  for  goods  of  an 
inferior  quality.  This  solvent  contains  small  quan- 
tities of  empyreumatic  substances  of  a  very  disagree- 
able odor,  and  the  latter  adheres  so  tenaciously  to 
the  fabrics,  as  to  render  its  removal  difficult  by  the 
treatment  with  steam,  and  a  slight  odor  always 
remains  behind. 

This  applies  also  to  coal-tar  oils,  and  for  this 
reason  these  solvents  should  be  tested  before  use, 


206    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

and  those  possessing  a  disagreeable  odor  in  a  re- 
markable degree  should  either  be  entirely  rejected 
or  subjected  to  a  second  rectification  in  order  to 
separate  as  much  as  possible  the  objectionable  pro- 
ducts. 

Manufacture  of  water-proof  fabrics  by  means  of  rub- 
ber compounds.  The  use  of  pure  or  vulcanized  rub- 
ber for  the  .  manufacture  of  water-proof  fabrics  is 
rather  expensive,  since,  besides  the  labor  required,  a 
large  portion  of  the  solvent  is  lost  even  with  the 
use  of  all  imaginable  precautions. 

In  order  to  manufacture  water-proof  fabrics  at  a 
smaller  cost,  less  expensive  bodies  than  rubber  are 
partly  used,  and  in  some  cases  this  material  is 
entirely  omitted  in  the  composition.  Coal-tar  and 
boiled  linseed  oil  have  proved  good  substitutes  for  a 
part  of  the  rubber,  as  they  furnish  compositions 
quite  suitable  for  many  purposes,  for  instance,  for 
so-called  rubber  shoes,  they  being  at  present  more 
frequently  used  for  this  purpose  than  pure  rubber. 

For  the  preparation  of  compounds  which,  besides 
rubber,  are  to  contain  linseed  oil,  the  latter  is 
heated  until  decomposition  takes  place.  For  this 
purpose  it  is  brought  into  a  boiler  of  a  sufficient 
capacity  to  contain  at  least  three  times  the  quantity 
of  oil,  as  the  latter  expands  very  much  during 
heating. 

The  oil  should  be  heated  as  quickly  as  possible  to 
from  302°  to  320°  F.,  and  kept  at  that  temperature 
for  several  hours.  The  fire  is  then  increased  to 
such  an  extent  that  the  oil  apparently  boils,  this 


ARTICLES    FROM    SOFT    RUBBER.  207 

being  the  stage  of  its  decomposition.  The  heating 
is  continued  until  a  sample  taken  from  the  boiler 
with  a  wooden  spatula  runs  off  in  long,  viscid 
threads. 

The  oil  thus  prepared  possesses  the  properties  of 
a  quickly-drying  varnish,  and  until  it  is  used  must 
be  protected  against  the  action  of  the  air  to  prevent 
it  from  drying  in.  For  this  purpose,  after  it  has 
become  cold,  it  is  put  in  a  vessel,  and  is  covered 
with  a  layer  of  water. 

The  purified  rubber  is  dissolved  in  oil  of  turpen- 
tine, which  is  generally  used  as  a  solvent  in  this 
case,  and  the  solution  compounded  with  a  certain 
quantity  of  boiled  oil,  the  latter  depending  entirely 
on  the  pleasure  of  the  manufacturer,  as  the  solution 
can  be  mixed  with  any  desired  quantity  of  it. 
When  the  first  coating  is  dry,  a  second  or  a  third  is 
applied,  as  may  be  found  necessary,  and  finally  one 
consisting  of  boiled  oil  alone,  to  which  has  been 
added  some  lampblack  or  any  other  coloring  matter. 

The  tissues  can  be  coated  by  using  the  same 
apparatus  employed  for  preparing  fabrics  with  pure 
rubber,  or  by  stretching  them  over  a  frame  and 
applying  the  composition  with  a  flat  brush. 

When  such  tissues  have  been  prepared  with 
proper  care,  they  are  especially  well  adapted  for  the 
manufacture  of  rubber  shoes.  The  separate  parts 
of  the  shoes  are  cut  from  it  according  to  patterns, 
and  cemented  together  over  a  last  with  rubber  solu- 
tions. The  soles  are  manufactured  either  of  vulcan- 
ized rubber  or  may  be  made  of  the  same  tissue,  but 


208    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

in  the  latter  case  either  very  thick  tissues  are  used 
or  several  layers  of  the  fabric,  employed  for  the 
uppers,  are  joined  together  by  pressing  them  while 
they  are  still  sticky,  in  order  to  make  the  soles  more 
durable. 

If  it  is  desired  that  the  boiled  oil  should  dry  as 
quickly  as  possible,  a  small  quantity  of  sugar  of 
lead  is  added  to  it  before  it  is  boiled  ;  one  per  cent. 
of  the  weight  of  the  oil  being  sufficient  for  the 
purpose. 

When  coal  tar  is  to  be  added  to  the  rubber,  it 
must  first  be  boiled,  until  a  mass  of  the  consistency 
of  Burgundy  pitch  is  formed.  While  still  hot,  it  is 
kneaded  together  with  and  worked  in  the  same 
manner  as  pure  rubber.  This  composition  can  be 
vulcanized*  by  adding  sulphur  to  it  during  the 
mechanical  treatment,  and  subjecting  it  to  the 
heating  process,  but  the  quantity  of  sulphur  added 
must  be  somewhat  larger  than  that  required  for 
pure  rubber. 

Water-proof  tissues  may  also  be  prepared  by 
using  a  rubber  lacquer,  which  will  be  described 
later  on.  In  regard  to  pliability  and  lustre,  the 
quality  of  the  coating  will  largely  depend  on  that 
of  the  varnish  used. 

Rubber  felt,  felt  paper,  or  Clark's  patent  felt,  is  used 
for  a  variety  of  purposes,  such  as  covering  damp 
walls,  protecting  silk  and  other  wares  from  damp- 
ness during  water-transit,  covering  telegraph  wire, 
roofing,  etc.  Although  rubber  is  now  used,  gutta- 
percha,  alone  or  mixed  with  resins  and  other  mat- 


ARTICLES    FROM    SOFT    RUBBER.  209 

ters,  has  been  employed.  A  pair  of  ordinary  mix- 
ing rolls,  running  at  equal  speeds,  receive  over 
each  a  cotton  fleece,  which  is  delivered  from  the 
carding  machines  stationed  on  opposite  sides,  so 
that  the  two  fleeces  enter  together  between  the 
rolls,  and  passing  down  through  an  opening  in  the 
floor  are  led  away  or  rolled  up.  A  sort  of  dough 
is  carefully  laid  between  the  rolls,  and  as  the  fleeces 
pass  through,  the  rubber  is  squeezed  into  them. 
The  fabric  is  vulcanized  by  incorporating  sulphur 
with  the  rubber  mixtures,  and  heating  in  the  same 
way  as  ordinary  spread  fabrics.  If  made  with  a 
good  quality  of  rubber  and  naphtha,  it  should  not 
feel  clammy  nor  soft,  but  should  be  dry  and  tough. 
Paper  can  be  similarly  treated,  and  for  damp  walls, 
etc.,  would  in  many  cases  be  as  useful  as  cotton, 
while  much  cheaper. 

Fabrication  of  elastic  webbings.  Genuine  elastic 
webbing  can  only  be  manufactured  with  the  use  of 
rubber.  Sheets  or  threads  of  the  latter  material 
may  be  employed,  though  sheets  are  only  of  secon- 
dary importance,  threads  being  chiefly  used  for  the 
larger  portion  of  these  fabrics. 

For  the  manufacture  of  elastic  webbings  with 
the  use  of  sheet  rubber,  closely  woven  tissues,  the 
individual  threads  of  which  possess  a  considerable 
degree  of  elasticity,  have  to  be  employed.  The 
tissues  are  stretched  over  a  frame  brushed  over 
with  rubber  solution,  and  then  covered  with  a  sheet 
of  rubber  which  has  been  stretched  in  the  same 
manner  as  that  used  for  threads  previously  de- 
14 


210    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

scribed.  Upon  this  sheet  is  placed  the  second 
tissue,  also  previously  brushed  over  with  rubber 
solution.  When  dry  the  fabric  thus  prepared  is 
exposed  to  a  temperature  of  from  140°  to  158°  F. 
in  order  to  restore  the  elasticity  of  the  rubber. 
Sheets  of  vulcanized  rubber,  if  used,  must  first  be 
partly  desulphurized  and  roughened  with  pumice 
stone  to  make  the  solution  adhere  to  them.  They 
are  then  worked  in  the  same  manner  as  above 
described. 

The  threads  to  be  used  for  webbing  must  first  be 
subjected  to  stretching.  For  this  purpose  they  are 
placed  in  warm  water  and  allowed  to  remain  there 
for  some  time,  whereby  they  acquire  a  great  degree 
of  ductility.  They  are  then  wound  upon  reels, 
being  strongly  stretched  during  the  process,  and 
exposed  to  as  cold  a  temperature  as  possible,  until 
they  have  lost  all  elasticity.  For  this  reason  it  is 
advisable  to  arrange  the  work  so  that  the  operation 
of  stretching  the  threads  can  be  dono  in  the  cold 
season  of  the  year. 

Threads,  which  have  been  properly  stretched 
and  cooled  off,  should  not  contract  when  taken 
from  the  reels  nor  show  any  perceptible  elasticity. 
Should  a  thread  break  during  stretching,  the  ap- 
paratus is  stopped,  the  place  of  rupture  cut  obliquely 
with  a  pair  of  sharp  scissors,  and  the  freshly  cut 
surfaces  joined  by  pressing  them  together. 

The  weaving  of  rubber  threads  is  done  by  form- 
ing a  kind  of  net  consisting  of  six  or  seven  threads 
of  any  kind  of  yarn  around  each  thread,  and  these 


ARTICLES    FROM    SOFT    RUBBER.  211 

overspun  threads  are  then  joined  together  by  a 
woof.  They  may  also  be  wound  upon  the  beam 
as  a  chain  and  provided  with  a  woof  of  ordinary 
yarn. 

Another  method  of  preparing  elastic  webbings, 
but  furnishing  a  less  durable  article,  consists  in 
placing  the  threads  parallel  along-side  of  each  other 
upon  a  tissue  which  has  been  brushed  over  with 
rubber  solution,  and  covering  them  with  a  similar 
tissue.  They  are  then  cemented  together  by  pass- 
ing them  through  between  powerful  rolls. 

Tissues  prepared  in  either  manner  are  finally 
finished  by  passing  them  through  between  rolls 
heated  by  steam,  which  impart  to  them  a  tempera- 
ture of  from  140°  to  158°  F.  The  rubber  having 
become  inelastic  by  exposure  to  a  low  temperature, 
assumes  by  this  its  original  elasticity.  The  stretched 
threads  contract  and  effect  also  the  contraction  of 
the  tissue  joined  with  them. 

When  threads  of  vulcanized  rubber  are  to  be  used 
in  the  manufacture  of  elastic  webbing,  the  process 
must  be  changed  in  a  corresponding  manner,  as 
vulcanized  rubber  does  not  possess  the  property  of 
retaining  the  length  given  to  it  by  stretching,  but 
will  contract  to  its  original  length  when  the  tension 
is  discontinued. 

In  this  case  the  loom  must  be  so  arranged  that 
the  threads  are  firmly  stretched  while  they  are 
woven  and  the  finished  woven  material  must  also 
be  subjected  to  such  tension.  The  power  acting 
upon  the  tissue  is  only  released  when  the  latter  is 


212   INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

entirely  finished,  when  it  will  contract  to  the  orig- 
inal length  of  the  threads. 

Recovery  of  solvents.  For  the  recovery  of  vapors 
of  henzene,  naphtha  arid  other  very  volatile  fluids 
used  in  the  manufacture  of  rubber  articles,  C.  A. 
Burghardt's  condensing  apparatus,  shown  in  Fig. 

FIG.  15. 


15,  is  very  suitable.  It  consists  of  a  boiler  com- 
posed of  annular  pieces  a,  and  surrounded  by  the 
vessel  c,  which  contains  the  cooling  water.  Between 
the  annular  pieces  a  are  fixed  steam-tight  the  cross 
bottoms  b  of  wire-netting  in  such  a  manner  that 
outside  the  boiler  they  project  into  the  cooling 
water  whereby  they  are  cooled  off.  The  vapors  to 


ARTICLES    FROM    SOFT    RUBBER.  213 

be  liquefied  are  conveyed  to  the  apparatus  through 
the  pipe  d,  or  sucked  in  by  means  of  a  suction 
apparatus  through  e.  In  their  passage  the  vapors 
are  condensed  on  the  cooled  cross-bottoms  b,  and 
pass  through  /  into  the  collecting  vessel  g,  which  is 
also  connected  by  the  pipe  h  with  the  boiler,  the 
object  of  this  connection  being  the  condensation  of 
any  vapors  evolving  from  g. 


CHAPTER  VII. 

RUBBER  VARNISHES  AND  LACQUERS. 

THE  properties  of  rubber,  especially  its  elasticity 
and  chemical  indifference,  make  it  particularly 
suitable  for  the  manufacture  of  varnishes  and 
lacquers,  and  there  being  a  constantly  increasing 
demand  for  these  products,  waste  which  could  not 
be  utilized  in  any  other  manner  can  be  profitably 
employed  for  this  purpose. 

The  first  step  required  is  to  transform  the  rubber 
into  a  solution,  the  solvents  which  have  frequently 
been  referred  to  being  well  adapted  for  the  purpose. 
However,  in  preparing  such  solutions,  many  things 
have  to  be  observed  in  order  to  obtain  them  of 
uniform  quality,  and  as  they  are  used  for  many 
other  purposes  besides  the  preparation  of  varnishes, 
it  will  be  of  interest  briefly  to  describe  the  method 
of  preparing  them. 

Preparation  of  rubber  solutions.  Rubber  solutions 
for  manufacturing  purposes  are,  as  a  rule,  prepared 
on  a  large  scale,  iron  vessels  hermetically  closed 
being  used  for  the  purpose.  The  rubber  is  cut  up 
in  small  pieces,  and  the  solvent  should  be  as  free 
from  water  as  possible. 

Although  the  Different  varieties  of  rubber  possess, 
(214) 


KUBBER    VARNISHES    AND    LACQUERS.  215 

as  a  rule,  the  same  chemical  composition,  they  show 
considerable  difference  in  their  behavior  towards 
solvents.  While,  for  instance,  one  variety  may 
readily  dissolve  in  oil  of  turpentine,  another  does  so" 
with  difficulty.  It  is,  therefore,  advisable  to  make 
a  preliminary  test  with  small  quantities  of  rubber 
and  solvent. 

The  most  favorable  results  are  obtained  by  add- 
ing from  5  to  40  per  cent,  of  highly  rectified  alcohol 
to  the  solvent,  the  good  effect  produced  thereby 
being  very  likely  due  to  the  property  in  alcohol  of 
vigorously  absorbing  water. 

If  carbon  di sulphide  or  benzene  is  used  as  a 
solvent,  special  precautions  to  prevent  volatilization 
have  to  be  employed.  The  top  of  the  vessel  for 
dissolving  the  rubber  should  be  provided  with  a 
broad  rim,  upon  which  a  ring  of  vulcanized  rubber 
is  laid,  and  after  the  lid  of  the  vessel  is  placed  upon 
this,  it  should  be  held  down  by  placing  heavy 
weights  upon  it.  The  vessel  is  also  provided  with 
a  stirring  apparatus,  and  in  its  general  arrangement 
very  much  resembles  that  used  for  bleaching  rubber 
(Fig.  10). 

The  dissolving  powrer  of  most  fluids  is  increased 
by  heat,  and  the  solution  of  rubber  can  be  much 
accelerated  by  placing  the  apparatus  in  a  boiler  filled 
with  water  and  heating  the  latter.  With  carbon 
disulphide  the  temperature  should  not  be  above 
104°  F.,  with  benzene,  not  above  140°  F.,  and  with 
oil  of  turpentine  or  rectified  petroleum  not  over 
212°  F.  But  heating  should  be  done  only  towards 
the  end  of  the  operation. 


216    INDIA  RUBBER, GUTTA  PERCHA, BALATA. 

Generally  24  to  30  hours  are  required  for  effecting 
complete  solution,  but  as  the  time  may  be  consider- 
ably shortened  by  heating  and  repeatedly  stirring 
the  mass,  it  is  advisable  to  arrange  the  stirring 
apparatus  in  such  a  manner  that  it  is  connected  by 
a  pulley  with  the  engine  of  the  factory  and  can  be 
constantly  kept  slowly  revolving. 

When  the  fluid  which  is  formed  after  the  solvent 
has  acted  upon  the  rubber  for  a  sufficiently  long 
time  is  examined  in  a  glass,  it  will  be  observed 
that  it  is  never  uniform,  but  that  small  lumps  of 
more  or  less  swollen  rubber  float  in  it.  These  can 
never  be  completely  dissolved  even  by  using  very 
large  quantities  of  the  solvent. 

Therefore,  to  obtain  uniform  solutions,  the  mass 
coming  from  the  apparatus  must  be  subjected  to 
mechanical  treatment,  and  this  consists  in  kneading 
or  squeezing  it  between  rolls.  If  carbon  disulphide 
or  another  volatile  solvent  has  been  employed,  this 
must  be  done  in  a  hermetically  closed  vessel  to  pre- 
vent heavy  losses  of  solvent  by  evaporation. 

Fig.  16  represents  an  apparatus  which  is  well 
adapted  for  kneading  rubber  solutions ;  it  is  ar- 
ranged as  follows : 

Two  smooth  rolls,  a  and  b,  of  equal  diameter,  lie 
in  a  box  K  of  wood  or  iron.  The  rolls  are  acted 
upon  by  cog-wheels  on  the  outside  of  the  box,  in 
such  a  manner  that  they  revolve  at  unequal  veloc- 
ities, and  are  placed  so  close  together  as  to  leave 
only  a  very  narrow  space  between  them.  The  rub- 
ber solution  to  be  kneaded  is  poured  into  the  sheet- 


RUBBER  VARNISHES  AND  LACQUERS. 


217 


iron  vessel  G,  in  the  bottom  of  which  is  a  slit  run- 
ning parallel  with  the  rolls.  Smoothing  blades  S, 
pressing  closely  against  the  rolls,  are  placed  on  both 
sides  of  them.  The  solution  which  is  scraped  by 
the  blades  from  the  rolls  flows  into  a  collecting 
vessel,  and  eventually  upon  a  second,  third,  or 
fourth  pair  of  rolls. 

To  control  the  flow  of  solution  upon  the  rolls 

FIG.  16. 


from  the  vessel  G,  there  is  a  metallic  wedge  fitting 
the  slit  in  the  bottom  of  the  vessel  G.  This  wedge 
can  be  raised  and  lowered  by  a  rod  projecting  above 
the  box,  and  the  discharge  of  the  solution  regulated 
thereby.  To  be  able  to  observe  the  flow  of  solu- 
tion, a  pane  of  glass  is  fitted  into  the  side  of  the  box. 
By  repeatedly  treating  the  partly  dissolved  and 
partly  swollen  mass  of  rubber  between  the  rolls,  an 
entirely  homogeneous  mass  is  finally  obtained,  the 


218        INDIA    RUBBER,"  GUTTA    PERCHA,  BALATA. 

consistency  of  which  will  of  course  depend  on  the 
proportions  of  rubber  and  solvent.  Very  thickly- 
fluid  solutions  can  be  used  for  casting  different 
articles  in  hollow  moulds,  somewhat  thinner  solu- 
tions for  cementing  together  pieces  of  rubber,  etc. 

By  reducing  the  swollen  masses  of  rubber,  which 
have  been  made  homogeneous  by  passing  them 
through  the  rolls,  with  ether,  chloroform,  oil  of 
turpentine,  etc.,  fluids  are  obtained  which  can  be 
used  as  varnishes  without  further  preparation.  In 
drying,  they  leave  behind  a  very  thin,  nearly  color- 
less film  of  rubber,  and  such  solutions  are  well 
adapted  for  coating  copper  plates  and  maps,  which 
can  then  be  cleansed  with  a  moist  sponge. 

For  many  purposes,  rubber  solutions  are  not 
used  by  themselves,  but  are  mixed  with  copal 
varnish,  boiled  linseed  oil,  dammar  resin,  etc. 
Varnishes  prepared  with  an  addition  of  resin- 
varnishes,  or  lacquers,  show  a  strong  lustre,  while 
pure  rubber  varnishes  (that  is,  solutions  of  pure 
rubber  alone)  possess  scarcely  any  lustre  whatever. 

Below  a  few  receipts  for  rubber  varnishes  for 
different  purposes  are  given  : 

Leather  Lacquer. 

Rubber       .         .         .1  part  by  weight. 

Dissolved  in  oil  of  tur- 
pentine .  .  .8  parts 

Mixed  with  fat  copal 
varnish  .  .  .6 

Boiled  with  linseed  oil     4        "  " 


RUBBER    VARNISHES    AND    LACQUERS.  219 

Varnish  for  Gilders. 

Rubber       .         .         .1  part  by  weight. 

Dissolved  in  rectified 

petroleum  .  .  8  parts  " 

Mixed  with  copal  var- 
nish .  4  "  " 

Varnish  for  Glass. 

Rubber       .         .         .1  part  by  weight. 

Dissolved    in  chloro- 
form       .         .         .60  parts  " 
Gum  mastic        .         .10        "            " 

This  varnish,  which  adheres  well  to  glass,  may 
be  colored  as  desired,  and  with  it  imitations  of 
flashed  glass  can  be  prepared,  and  glass  cemented 
to  glass.  It  is  also  well  adapted  for  fastening  let- 
ters of  glass  or  metal  upon  glass. 

A  varnish  which,  however,  dries  somewhat 
slowly,  is  prepared  by  cutting  up  1  Ib.  of  soft  rub- 
ber and  allowing  it  to  swell  up  in  J  Ib.  of  ether. 
The  mass  is  then  liquefied  by  heating  in  warm 
water ;  it  is  then  mixed  with  1  Ib.  of  warm  pale 
linseed  oil,  and  after  some  time  with  1  Ib.  of  heated 
oil  of  turpentine,  and  finally  filtered. 

For  varnishing  morocco,  Champagne  recommends 
the  following  preparation :  Allow  J  Ib.  of  rubber 
cut  up  into  small  pieces  to  stand  for  two  days  with 
1  Ib.  of  oil  of  turpentine,  then  stir  vigorously  and 
after  adding  1  Ib.  more  of  oil  of  turpentine,  complete 
solution  by  heating  in  the  water-bath.  Mix  1 J  Ibs. 


220    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

of  the  solution  with  2  Ibs.  of  pale  copal  varnish 
and  1J  Ibs.  of  boiled  linseed  oil,  and  gently  heat  for 
some  time  until  a  uniform  mixture  results. 

A  flexible  varnish  is  prepared  by  melting  1  Ib. 
of  colophon}^  gradually  adding  J  Ib.  of  rubber  cut 
up  in  small  pieces,  stirring  until  cold,  and  after 
adding  1  Ib.  of  hot  linseed  oil,  completing  solution 
by  heating. 

A  water-proof  coating  for  shoes  and  boots  is  pre- 
pared as  follows  :  Soften  1  part  of  rubber  in  hot 
water,  cut  it  up  in  small  pieces  with  a  pair  of 
scissors,  and  heat  gently  together  with  1J  parts  of 
lard  and  6  parts  of  fish-oil,  until  solution  is  com- 
plete. Apply  the  solution  while  warm  to  the 
leather.  It  dries  in  the  air  to  a  lustrous  coating, 
and  becomes  so  hard  that  it  does  not  stick. 

A  solution  for  repairing  rubber  shoes  is  prepared 
as  follows  :  Pour  12  to  14  parts  of  carbon  disulphide 
over  2  parts  of  rubber  cut  up  in  small  pieces,  and 
let  the  vessel  containing  the  mass  stand  in  a  water 
bath  at  86°  F.  until  solution  is  effected.  The  solu- 
tion is  of  a  paste-like  consistency,  and  to  prevent  it 
from  hardening  too  rapidly,  reduce  it  with  a  solution 
of  rubber  and  colophony  in  oil  of  turpentine,  for  the 
preparation  of  which  melt  at  a  moderate  heat  1  part 
of  rubber,  add  to  it  \  part  of  colophony,  and  when 
both  are  melted  together,  add  sufficient  oil  of 
turpentine. 

Marine  glue.  The  preparation  known  by  this 
name  is  an  excellent  rubber  varnish  for  protecting 
wood  and  metal  against  the  action  of  water.  It 


RUBBER  VARNISHES  AND  LACQUERS.     221 

consists  of  a  solution  of  1  part  of  rubber  in  12  parts 
of  rectified  petroleum,  which  is  combined  by  heat- 
ing and  stirring  with  6  parts  of  shellac  or  asphal- 
tum.  It  should  be  applied  at  a  temperature  of 
from  266°  to  284°  F. 

Marine  glue  for  damp  walls.  It  is  frequently  a 
very  difficult  matter  to  keep  the  basement  walls  of 
houses  entirely  dry.  Generally  they  absorb  so  much 
moisture  from  the  ground  that  the  glue  which  has 
been  mixed  with  the  paint  commences  to  mould, 
and  the  painter's  work  falls  off,  or  in  case  the  room 
is  papered  the  wall-paper  puffs  up  arid  becomes 
stained.  These  evils  can  be  best  avoided  by  using 
the  following  marine  glue  : 

Parts. 

Rubber  .  .  .  .  .  10 
Whiting  .  .  .  .  .  10 
Oil  of  turpentine  ....  20 
Carbon  disulphide  ...  10 
Colophony  .....  5 

Asphaltum 5 

These  substances  are  put  in.  a  large  bottle,  and 
this  is  closed  as  air-tight  as  possible.  It  is  then  put 
in  a  moderately  warm  place  and  allowed  to  stand 
until  the  soluble  substances  have  become  dissolved  ; 
this  can  be  hastened  by  frequently  shaking  the 
bottle.  The  wall  to  be  dried  is  first  thoroughly 
cleansed,  the  glue  is  then  applied  with  a  flat  brush, 
and  should  be  laid  on  about  8  to  12  inches  higher 
up  than  the  wall  appears  to  be  damp.  Paper  which 


222    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

will  adhere  very -tightly  to  it  is  then  laid  over  the 
glue  while  it  is  still  sticky. 

The  wall-paper  can  be  immediately  pasted  upon 
this  paper,  and  if  the  glue  has  been  prepared  with 
due  care,  will  never  fall  off,  as  the  wall  will  always 
be  dry. 

Jeffery's  marine  glue.  This  consists  of  rubber  3 
parts,  undistilled  coal  tar  36,  asphalt  6.  The 
rubber  is  cut  up  in  small  pieces  and  dissolved  in 
the  coal  tar,  and  the  asphaltum  is  then  added. 

The  marine  glue  obtained  in  this  manner  is  so 
hard  that  it  cannot  be  readily  melted  over  an  open 
fire.  When  it  is  to  be  used,  it  is  first  softened  in  a 
water-bath,  and  can  then  be  made  more  liquid  over 
a  coal  fire  without  running  the  risk  of  scorching  it. 

An  excellent  transparent  cement  for  glass  upon 
glass  is  obtained  by  dissolving  75  parts  of  rubber 
and  15  parts  of  mastic  in  60  parts  of  chloroform. 

For  cementing  rubber  to  metal,  a  solution  of  1 
part  of  shellac  in  10  parts  of  ammonia  is  used. 

Hard  rubber  lacquer.  Waste  and  broken  articles 
occurring  in  the  manufacture  of  hard  rubber  can  be 
used  for  one  purpose  only,  namely,  for  the  prepara- 
tion of  lacquer. 

The  pieces  of  hard  rubber  are  melted  in  an  iron 
pot  and  must  be  constantly  stirred  to  prevent 
scorching.  The  melted  mass  is  poured  in  a  thin 
stream  upon  iron  plates,  where  it  congeals  to  a 
brittle  mass  resembling  asphaltum.  The  latter  is 
broken  into  pieces,  which  are  put  in  a  bottle,  and 
rectified  petroleum,  or,  what  is  still  better,  benzol  is 


RUBBER  VARNISHES  AND  LACQUERS.     223 

poured  over  them.  The  quantity  of  solvent  added 
must  be  sufficient  to  produce  a  fluid  which  can  be 
easily  applied  with  a  brush.  The  fluid  is  allowed 
to  stand  for  a  considerable  time,  during  which  the 
foreign  substances  mixed  with  the  hard  rubber,  and 
which  are  insoluble  in  petroleum  or  benzol,  settle  to 
the  bottom,  and  the  solution  is  then  poured  off  very 
carefully. 

Hard  rubber  lacquer  when  applied  to  wood  or 
metal  forms  a  brownish-yellow  to  black  coating 
which  strongly  resists  atmospheric  influences,  and 
for  this  reason  is  especially  adapted  for  varnishing 
machines  erected  in  the  open  air. 


II.    GUTTA  PERCHA. 
CHAPTER  VIII. 

RAW    MATERIAL. 

GUTTA-PERCHA,*  as  regards  its  natural  formation 
and  composition  is  a  plant-product  similar  to 
rubber.  It  is  obtained  from  the  milky  juice  of 
certain  trees,  and  it  is  also  a  hydrocarbon  composed 
of  about  equal  parts  of  carbon  and  hydrogen. 

Historical  Review. 

Gutta-percha  was  first  brought  to  Europe,  in  1866, 
by  the  English  traveler  John  Tradescant,  who  called 
it  "  mazer  wood."  The  sample,  which  he  brought 
home  from  his  travels,  was  considered  a  great 
curiosity,  and  may  be  seen  at  the  present  day  in  the 
Museum  Tradescantium,  South  Lambeth,  London. 
However,  no  one  took  the  trouble  to  examine  this 
new  product,  and  still  less  to  apply  it  to  practical 
use. 

Even  at  the  commencement  of  the  19th  century 
but  little  notice  was  taken  of  it.  Scientists  and 
manufacturers  were  occupied  with  the  examination 

*  Latin :  gummi  plasticum;  French  and  German:  gutta- 
percha. 

(224) 


RAW    MATERIAL.  225 

of  rubber,  and  gutta-percha  was  at  tbat  time  gener- 
ally considered  as  a  non-clastic,  inferior  quality  of 
rubber,  which  could  not  compete  with  the  Brazilian 
and  East  Indian  products.  Only  its  defects  were 
seen,  and  no  one  had  the  remotest  idea  of  those  quali- 
ties which  at  present  make  gutta-percha  an  inval- 
uable material. 

In    1832,   Dr.   William  Montgomery,   who   prac- 
ticed medicine  in  Singapore,  entered  into  conversa- 
tion   with    a    Malay    laborer.       While   talking    he 
observed  the  handle  of  a  hoe,  and  he  heard  with 
surprise   that  its   substance,    however    hard   it    ap- 
peared to  be,  could  be  softened  by  immersion  into 
hot  water,  and  could  thereupon   assume  and   pre- 
serve any   desired   shape.     The    experiment  being 
immediately  made,  the  assertion  of  the  Malay  was 
fully  confirmed.     On  further  inquiry,  that  excellent 
quality  of  the  substance  in  question  was  found  to 
have  been  long  known  among  the  natives  of  Java, 
where    it  was   used   for  manufacturing  canes  and 
handles  of  whips,  as  well  as  of  various  other  imple- 
ments, and  especially  of  knives  and  daggers.     Dr. 
Montgomery  procured  a  sample  of  this  remarkable 
substance  and  on  experimenting  with  it,  found  that 
this  new  gum  was  in  certain  respects  superior  to 
rubber  for  surgical  instruments,  since  the  latter  be- 
came soon  sticky  under  the  influence  of  the  moist 
warm  temperature   of  the  inter-tropical   zone.     In 
1843,   he    reported    his    discovery    to    the    Medical 
Board  at  Calcutta,  and  at  the  same  time  instructed 
his  friend,  Dr.  Jose  D'Almeida,  to  communicate  his 
15       * 


226    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

discovery  to  the  Royal  Society  of  Arts,  which 
awarded  to  Dr.  Montgomery  its  gold  medal. 

For  the  purpose  of  experimenting  D'Almeida 
furnished  small  quantities  of  the  so-called  gum  to 
English  manufacturers,  but  these  experiments  were 
not  encouraging,  because  the  special  value  of  the 
material  was  not  recognized.  However,  a  portion 
of  the  samples  reached  Paris,  and  were  there  util- 
ized for  probes  and  other  surgical  instruments, 
which  were  formerly  made  from  rubber. 

In  1845,  Lagrenee,  returning  from  a  voyage, 
procured  in  Singapore  quite  a  considerable  quantity 
of  gutta  percha,  which  he  presented  to  the  French 
Minister  of  Commerce.  The  latter  placed  it  at 
the  disposal  of  some  manufacturers,  and  in  the  fol- 
lowing year,  Alexandre,  Cabriot  and  Duclos  ob- 
tained the  first  patent  for  the  utilization  of  gutta 
percha. 

From  this  patent  (July  28,  1846)  dates  the  intro- 
duction of  gutta  percha  and  the  creation  of  a  new 
industry.  It  would  lead  too  far  to  discuss  the 
various  stages  through  which  this  industry  had  to 
pass  before  gutta  percha  was  thoroughly  understood 
and  finally  took  the  place  in  the  industries  which 
properly  belongs  to  it.  It  may  suffice  to  say  that 
attempts  were  successively  made  to  use  this  new 
product  for  all  articles  formerly  made  of  rubber. 
However,  in  fact,  all  these  experiments  were  con- 
trary to  the  characteristic  properties  of  gutta-percha, 
the  greatest  difficulty  being  that  it  becomes  plastic 
in  the  heat.  Attempts  were  made  to  overcome*  this 


RAW    MATERIAL.  227 

defect  by  vulcanization,  which  had  been  so  success- 
ful with  rubber.  But  sulphur  acts  upon  gutta 
percha  in  an  entirely  different  way  from  rubber,  and 
thus  the  hopes  which  had  been  entertained  were  of 
short  duration.  However,  the  discovery  of  the 
peculiar  properties  of  gutta  percha  were  made  just 
at  the  proper  time,  when  dynamic  electricity  com- 
menced to  play  an  important  role.  It  was  found  to 
be  an  excellent  insulating  material,  and  that  it 
remains  unaltered  in  water  and  especially  in  salt 
water,  which  led  to  the"  idea  of  using  it  as  an  en- 
veloping material  for  submarine  telegraph  cables. 
The  honor  of  first  constructing  telegraph  lines 
insulated  with  gutta  percha  belongs  to  Werner 
Siemens,  who,  in  1847,  built  such  a  line  on  a  Ger- 
man railroad.  Wheatstone,  as  early  as  1837,  had 
the  idea  of  connecting  England  by  telegraph  with 
the  Continent,  and  he  considered  gutta  percha  as 
the  most  suitable  material  for  use  in  the  construction 
of  submarine  cables.  However,  his  idea  was  first 
actually  carried  out  by  Walter  Breit,  who,  January 
10,  1849,  laid  at  Folkestone  a  submarine  cable,  two 
miles  long,  insulated  with  gutta  percha.  In  the 
meantime  gutta  percha  was  found  to  be  an  excellent 
material  for  .sharp  moulds  such  as  are  required  in 
galvanoplasty,  and  its  resistance  to  acids  led  to  the 
fabrication  of  receivers,  funnels  and  tubes  for  use  in 
chemical  factories,  photographic  and  other  labora- 
tories. 

Occurrence  of  Gutta  PercJia. 

Most  of  the  gutta  percha  plants  belong  to  the  nat- 


228        INDIA    RUBBER,  GUTTA    PERCH  A,  BALATA. 

ural  order  Sapotacese  growing  in  the  Malay  Penin- 
sula.    The  most  important  are  : 

1 .  Dichopsis  gutta,  or  Isonandra  gutta,  or  Palaquium 
gutta.     It  attains  a  height  of  60  to  80  feet,  with  a 
diameter  of  2  to  4  feet.     The  leaves  are  obovate- 
oblong  and  entire,  pale-green  on  the  upper  side  and 
covered  beneath  with  short  reddish-brown  shining 
down.     The  flowers  are  arranged  in  clusters  of  3  or 
4  in  the  axis  of  the  leaves.     The  fruit,  about  an 
inch  long,  is  of  an  ovoid  shape,  and  is  eaten  by  the 
Malays.     The  wood   is  soft,   fibrous,   spongy,  of  a 
pale  color,  and  marked  with  black  lines,  these  being 
reservoirs  of  gutta  percha.     The  gutta  as  it  flows 
from  the  tree  is  of  a  grayish  hue,  occasionally  with 
a  somewhat  roseate  tinge. 

2.  Dichopsis  oblongifolium.     This  variety  is  found 
in  Borneo  and  differs  chiefly  from  the  preceding  in 
having   oblong   instead    of  obovate-oblong   leaves. 
The  gutta  obtained   from   this  tree  is  excellent  as 
regards    uniformity    and    durability.       When    free 
from  bark  and  wood  it  is  very  tough  and  elastic  so 
that  it  can   be  folded   together  without   breaking. 
When  dipped  in  hot  water  it  can  be  kneaded  and 
moulded  without  becoming  sticky,  and  on  cooling 
reassumes  its  former  solidity.     Its  color  varies  be- 
tween red  and  dark  brown.     Like  all  other  varieties 
of  gutta  percha  the  juice  as  it  exudes  from  the  tree 
is  milk-white,  the  brown  color  being  imparted  to  it 
by  being  mixed  with   particles  of  wood  and   bark, 
which  in  boiling  and  purifying  the  gutta  yield  to  it 
their  coloring  matter. 


RAW    MATERIAL.  229 

3.  Dichopsis  calophylla  (Benth.  and  Hook.)   ap- 
pears to  be  the  Mayang  Baton  mentioned  by  Selig- 
mann-Lni.     It  yields  a  paler  gutta  of  a  more  reddish 
color,  inferior  in  quality  and  stiffness  to  Dichopsis 
oblongifolium. 

4.  Dichopsis   selendit    yields  a  very   bard    gutta 
suitable  for  the  manufacture  of  cables.     Mixed  with 
other  varieties,  it  may,  however,  be  also  employed 
for  other  purposes. 

5.  Dichopsis  Krantziana,  is  a  tree  called  in  Cam- 
bodia by  the  natives   Thior,  and  in  Cochin-China, 
Chay.      Botanically   it   resembles   Isonandra   gutta. 
The  gutta  obtained  from  it  is  of  an  inferior  quality, 
and  even  when  mixed  with  other  varieties  does  not 
give  a  product  which  can  be  recommended. 

6.  Dichopsis  pustulatum  was  discovered  in  Perak, 
and  is  now  cultivated  in  Ceylon  as  a  gutta  percha 
tree. 

7.  Payena  Lerii  is  the  only  tree  belonging  to  the 
variety   Payena  which    yields  gutta.      It  was  dis- 
covered by  Brau  de  St.  Pol-Lias.     It  yields  a  very 
fair,  red  gutta. 

8.  Bassia  Parkii  is  of  importance  as  a  gutta  percha 
tree  among  the  Bassiese. 

9.  Mimusops.     The  product  of  this  plant  is  no 
longer  brought  into  commerce  under  the  name  of 
gutta  percha,  but  as  Balata.     Under  this  name  it 
has  brought  about  a  special  industry  which  occu- 
pies about  the  same  position  to  gutta  percha  as  the 
latter  does  towards  rubber,  and  hence  a  separate 
chapter  will  be  devoted  to  it. 


230    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

The  geographical  distribution  of  the  trees  pro- 
ducing gutta  percha  is  very  restricted,  the  limits 
being  about  6°  N.  and  S.  latitudes  and  100°  to 
120°  E.  longitude.  Many  of  the  best  varieties  are 
found  only  on  the  hill  slopes  at  a  distance  from  the 
sea-coast,  each  variety  forming  a  separate  grove  of 
from  200  to  500  trees,  with  high  forest  trees  above 
them.  They  grow  best  in  a  rich  light  loam  with  a 
rocky  subsoil. 

Manner  of  Obtaining  Crude  Gutta  Percha. 

The  collection  of  gutta-percha  generally  takes 
place  directly  after  the  rainy  season,  as  in- the  dry 
season  the  gutta  does  not  flow  so  readily,  while  dur- 
ing the  rains,  ague  and  jungle  fever  are  most  pre- 
valent, and  the  gutta  is  liable  to  be  washed  away 
from  the  felled  trees. 

The  methods  of  extracting  the  gutta-percha  are 
much  the  same  amongst  the  Malays,  Chinese  and 
Dyaks.  The  trees  are  cut  down  just  above  the 
buttresses,  and  for  this  purpose  a  staging  about  14 
to  16  feet  high  is  erected.  The  tools  used  in  felling 
are  either  "  billiongs  "  or  "  parangs."  A  billiong  is 
a  kind  of  axe,  with  a  blade  of  a  chisel-like  form, 
and  the  tang  is  secured  at  right  angles  to  a  handle 
by  means  of  a  lashing  of  rattan  or  cane.  The 
Chinese  sometimes  use  an  axe  perfectly  wedge- 
shaped.  The  parang  looks  more  like  a  sword  bay- 
onet, and  in  the  hands  of  a  Malay  is  a  box  of  tools 
in  itself,  as  with  it  he  can  cut  up  his  food,  fell  a 
tree,  build  a  house,  or  defend  himself. 


RAW    MATERIAL.  231 

When  the  tree  is  felled  the  branches  are  quickly 
lopped  off  to  prevent  the  ascent  of  the  gutta  to  the 
leaves.  Narrow,  strips  of  bark,  about  an  inch  broad 
and  6  inches  apart,  are  then  removed,  but  not  all 
round  the  tree,  as  its  underpart  in  its  fall  becomes 
buried  in  the  soft  earth,  much  sap  being  thus  lost. 
Some  natives  beat  the  bark  with  mallets  to  accel- 
erate the  flow  of  milk  or  gutta.  The  milk  flows 
slowly  and  rapidly  concretes,  and,  according  to  its 
source,  may  vary  from  yellowish  white  to  reddish 
and  even  brownish  in  hue.  The  gutta  as  it  flows  is 
received  in  hollow  bamboos,  doubled  up  leaves, 
spathes  of  palms,  pieces  of  bark,  cocoanut  shells,  or 
in  holes  scraped  in  the  ground. 

According  to  observations  made  by  Leon  Brasse 
and  Seligmann-Lui  in  the  regions  of  production, 
gutta-percha  is  prepared  in  various  ways.  Thinner 
milky  juices,  like  that  of  Payena,  are  brought  in  a 
liquid  state  into  the  hut  of  the  native,  while  thicker 
juices,  such  as  those  of  Dichopsis,  become  mixed  in 
exuding  with  particles  of  wood  and  concrete  still 
more  during  transport.  The  native  removes  with 
the  hand  the  coarsest  splinters  of  wood  and  bark 
and  then  throws  the  mass  into  a  pot  of  boiling 
water.  The  gutta  becomes  soft  so  that  it  can  be 
kneaded  and  is  converted  into  a  compact  mass. 
Good  qualities  do  not  stick  to  the  fingers.  The 
mass  is  worked  into  strips  as  thin,  and  even  as  pos- 
sible, whereby  the  greater  portion  of  the  particles  of 
wood  come  to  the  surface  and  can  be  removed  by 
cold,  rubbing  or  in  some  other  manner.  As  a  rule 


232        INDIA    RUBBER,  GUTIA    PERCHA,  BALATA. 

this  operation  is  twice  repeated.  The  gutta  is  then 
again  softened,  kneaded,  rolled  out  in  sheets,  washed 
and  rubbed  and  folded  into  blocks  of  various  sizes 
and  shapes.  Gutta  percha  twice  cleansed  is,  of 
course,  much  better  than  the  product  which  has 
been  but.once  manipulated  ;  yet  it  is  not  quite  pure, 
as  it  still  contains  a  considerable  quantity  of  par- 
ticles of  wood,  which,  when  the  gutta-percha  is  to 
be  used  for  industrial  purposes,  have  to  be  removed. 
In  Sumatra  the  gutta  is  not  purified,  but  just  the 
reverse,  is,  as  a  rule,  intentionally  adulterated  by 
the  addition  of  quantities  of  pulverized  bark.  In 
the  course  of  all  these  processes  the  gutta-percha 
changes  its  color.  While  originally  white  on  exud- 
ing from  the  tree,  by  being  boiled  it  acquires,  in 
consequence  of  the  admixture  of  bark  and  wood,  a 
darker  hue,  which  varies  in  the  different  varieties. 
While  the  gutta  of  Payena  becomes  yellowish  by  the 
influence  of  the  air,  that  of  DicJwpsis  is  only  colored 
by  the  coloring  matter  it  absorbs  during  boiling. 

Unmixed  gutta-percha,  i.  e.,  derived  from  one 
and  the  same  variety  of  plant,  is  seldom  found  in 
commerce.  When  the  collector  has  found  a  certain 
quantity  of  gutta  percha  of  good  quality,  but  not 
enough  to  sell  it  to  advantage,  he  looks  around  for  a 
tree  from  which  he  can  get  what  is  lacking.  How- 
ever, not  to  lose  time  in  hunting,  he  attacks  the  first 
tree  he  finds  and  takes  all  that  is  offered  until  the 
desired  quantity  is  obtained.  On  returning  to  his 
hut  he  mixes  everything  together.  This  custom  is 
so  general  that  it  is  impossible  to  procure  from  the 


f  uNlVERSn 
1    pf 


RAW    MATERIAL 


native  dealers  samples  of  each  kind.  The  most  suc- 
cessful mixture  is  frequently  designated  as  Balam- 
ttmbago,  even  when  the  juice  of  Dicliopsis  oblongi- 
foli'um  is  contained  in  it.  Experience,  however, 
has  taught  the  Malays  which  kinds  go  wrell  together 
and  which  interfere  with  each  other,  and  in  their 
own  interest  they  take  care  not  to  mix  the  latter. 

Regarding  the  yield  of  crude  product  obtained 
from  the  different  varieties  of  gutta-percha  trees,  it 
would  seem  that  this  is  largely  influenced  by  geo- 
graphic and  climatic  location,  the  age  of  the  trees, 
the  season  of  the  year  when  the  juice  is  collected, 
the  mode  of  felling  the  trees,  manner  of  gathering 
the  juice,  etc.  The  statements  in  reference  to  the 
yield  are  at  such  variance  as  to  leave  a  doubt  of  the 
correctness  of  any  of  them.  Thus  Burke  gives  the 
average  yield  from  full-grown  trees  as  11  ozs.  Ser- 
rulaz  states  that  a  gigantic  tree  felled  in  Pahang 
yielded  13J  ozs.,  while  Wray  gives  the  product  of  a 
Taban  merah  tree,  100  years  old,  as  2  Ibs.  5  ozs.,  and 
that  of  a  full-grown  Taban  putch  tree  as  2  Ibs  11 
ozs.  Logan,  on  the  other  hand,  .gives  the  average 
yield  of  a  tree,  for  Johor,  as  5J  Ibs.,  and  Oxley,  for 
Singapore,  as  13J  Ibs.  No  matter  which  of  these 
statements  may  be  correct,  the  fact  remains  that 
even  in  the  most  favorable  case  the  yield  of  a  tree 
is  small,  and  that  with  the  irrational  manner  in 
which  the  juice  is  collected,  the  trees  still  in  exist- 
ence will  become  more  and  more  decimated,  and 
that  there  is  danger  of  a  decrease  in  the  exportation 
and  finally  of  entire  exhaustion  of  the  sources. 


234    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

The  question  of  how  to  meet  this  danger  has  occu- 
pied many  minds,  and  finally  E.  Jungfleisch  con- 
ceived the  idea  of  overcoming  it  by  a  more  rational 
mode  of  harvesting.  An  examination  of  specimens 
of  plants  led  him  to  the  conclusion  that  gutta  is 
contained  in  all  parts  of  the  gutta-percha  tree,  not 
only  in  the  trunk,  but  also  in  other  organs,  and 
very  likely  in  far  greater  quantities  than  the 
Malays  could  extract  from  them.  In  his  report, 
in  1892,  to  the  Societe  d'encouragement,  Jung- 
fleisch states  that  experiments  have  shown  that 
there  are  several  solvents  with  the  assistance  of 
which  gutta-percha  can  be  extracted  from  the 
plant-cells,  toluene  having  proved  the  most  effec- 
tive. It  completely  dissolves  the  three  constituents 
of  gutta  percha — gutta,  albane,  and  fluavile — but 
with  the  exception  of  a  small  quantity  of  chloro- 
phyl,  very  little  of  the  other  substances  contained 
in  the  leaves,  bark  and  wood  passes  into  the  solu- 
tion. The  experiments  were  made  : 

1.  With  leaves  dried  in  the  air,  i.  e.,  leaves  ex- 
posed to  oxidation  by  the  air. 

2.  With  leaves  dipped  while  fresh  in  antiseptic 
water  and  then  dried. 

3.  With  dried  shoots  deprived  of  their  leaves. 

4.  With  dried  wood,  two  years  old  and  deprived 
of  its  leaves. 

All  these  parts  yielded  a  considerable  quantity  of 
gutta-percha. 

The  method  of  extracting  the  gutta  percha  by 
this  process  is  very  simple.  The  pulverized  mass, 


RAW    MATERIAL.  235 

i.  e.,  leaves,  shoots,  barks,  etc.,  is  heated  to  aboirt 
212°  F.,  and  then  mixed  with  a  solvent,  for  in- 
stance, toluene,  the  result  being  a  solution,  colored 
green  by  chlorophyl.  Direct  evaporation  of  the 
solvent  is  impossible  without  injury  to  the  product, 
and  hence  the  toluene  is  removed  by  means  of 
steam  of  at  the  utmost  212°  F.  One  part  of  steam 
carries  off  4  parts  of  toluene,  the  gutta-percha  re- 
maining behind.  For  the  complete  separation  of 
the  toluene  the  steam  is  allowed  to  act  for  some 
time  on  the  mass  kept  in  motion  and  at  a  tempera- 
ture of  212°  F. 

Besides  Jungfleisch  and  Serrulaz,  D.  Rigole,  Prof. 
Ramsay  and  Dr.  E.  Obach  have  occupied  them- 
selves with  the  gaining  of  gutta  percha  by  extrac- 
tion, and  numerous  apparatuses  have  been  con- 
structed for  the  purpose,  which  are  described  in 
Dr.  Obach's  "Cantor  Lectures  on  Gutta  Percha." 
London,  1808. 

Commercial  Gutta  Percha. 

The  principal  port  of  shipment  of  crude  gutta 
percha  is  Singapore.  Before  exportation  it  gener- 
ally undergoes  examination  and  classification  into 
parcels  according  to  quality.  As  received  in  the 
"godowns"  or  warehouses,  it  presents  great  diversi- 
ties in  condition,  shape,  size  and  color — from  crum- 
bling, hardly  coherent,  whitish  or  greyish  "  raw  " 
or  "  getah  muntali  "  fragments,  to  reddish  or  brown- 
ish blocks  as  hard  as  wood.  Sometimes  it  is  made 
up  into  all  manner  of  grotesque  shapes  of  animals, 


236    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

and  it  is  nearly  always  largely  adulterated  with 
sago  flour,  sawdust,  clay,  stones,  etc.  The  Chinese 
are  great  adepts  in  assorting  and  classifying  gutta, 
and  frequently  prepare  from  different  varieties  a 
certain  "  standard  sample,"  by  cutting  or  chopping 
the  material  into  thin  slices  and  boiling  with  water 
in  large  shallow  iron  pans,  keeping  the  contents 
constantly  stirred  with  poles,  and  adding  good  gutta- 
percha  and  even  cocoanut  oil  to  give  a  better  ap- 
pearance. When  sufficiently  boiled  the  gutta- 
percha  is  pressed  into  large  moulds,  and  is  then 
ready  for  shipment.  This  process  of  reboiling  is 
wholly  unnecessary,  and  in  some  cases  is  done  only 
to  get  rid  of  stuff  which  has  no  right  to  be  called 
gutta-percha. 

A  brief  summary  of  the  best  known  varieties  of 
gutta  percha,  including  their  commercial  names, 
place  of  origin,  form  in  which  they  are  brought  into 
commerce,  appearance,  properties,  etc.,  is  given 
below  : 

Pahang.  Origin :  State  of  Pahang,  east  coast  of 
the  Malay  Peninsula.  Form:  Generally  small 
pieces.  Pear-shaped  pieces  weigh  1  to  2  Ibs.;  rec- 
tangular oblate  pieces,  at  the  utmost  6  Ibs.  6  ozs. 
Appearance :  Yellowish  ;  seldom  red  ;  mostly  play- 
ing into  greenish.  Cut  surface  :  White-yellowish  ; 
very  seldom  yellow-reddish  ;  compact,  seldom  fol- 
iated. Nature  and  quantity  of  impurities :  Some  par- 
ticles of  wood  ;  30  per  cent.  Valuation  :  This  qual- 
ity works  up  very  well,  remains  for  a  long  time 
very  nervy,  and  on  cooling  rapidly  regains  its 


RAW    MATERIAL.  237 

original  hardness.  Nature  of  the  thread :  Somewhat 
wrinkly. 

Sandakan.  Origin :  In  the  North  Eastern  part  of 
Borneo.  Form :  Loaves  in  the  shape  of  a  parallel- 
epiped with  trapeziform  base  and  boat-shaped  elon- 
gation, weighing  4  Ibs.  Appearance:  Pale  yellow. 
Cut  surface:  White-yellowish,  very  seldom  yellow- 
reddish  ;  compact,  seldom  foliated.  Nature  and  quan- 
tity of  impurities :  Small  quantity  of  bark  ;  22  per 
cent.  Valuation:  Like  the  preceding.  Nature  of  the 
thread:  Smoother  than  the  preceding. 

Maragula.  Origin:  Not  known.  Form:  Very 
flat  loaves  weighing  2  Ibs.  or  less.  Also  flat  or  four- 
cornered  pressed  spindles  weighing  6  to  8  Ibs. 
Appearance:  White-gray,  with  grayer  spots.  Cut 
surface  :  Horny.  Nature  and  quantity  of  impurities  : 
The  mass  contains  no  irregular  particles  of  bark, 
but  regular  cut  pieces  are  found  which  no  doubt 
have  been  intentionally  added  ;  16  per  cent.  Valu- 
ation :  Very  hard,  rapidly  cooling  gutta.  Nature  of 
the  th read  :  \ V  ri n k  1  y . 

Bagan.  Origin:  Very  likely  between  Malacca 
and  Singapore.  Form :  Pear-shaped  pieces  weigh- 
ing 4  to  6  Ibs. ;  or  turnip-shaped  pieces  weighing 
12  to  17  Ibs.  Appearance:  Wine-red;  feels,  either 
cold  or  warm,  like  soap.  Cut  surface:  More  or  less 
rugged  ;  numerous  holes  due  to  the  imperfect 
cementing  together  of  the  separate  pieces  of  which 
the  large  pieces  are  composed.  Nature  and  quantity 
of  impurities :  Either  none  or  few  particles  of  bark  ; 
29  per  cent.  Valuation :  Quite  hard,  nervy,  and 


238   INDIA  RUBBER, GUTTA  PERCHA,  BALATA. 

rapidly  cooling  gutta.  Nature  of  the  thread:  Very 
smooth.  Smells  of  opium  ;  is  difficult  to  cleanse ; 
resembles  very  much  balata  in  its  behavior  in 
cleansing  and  spinning. 

Banjer-massin.  Origin:  South  Borneo.  Form : 
Clubs  about  32  inches  long  and  3{  to  of  inches  in 
diameter,  rounded  off  on  both  ends.  Also  parallel- 
epipeds ornamented  on  both  sides  with  sculptures, 
a  monster  upon  one  side  and  foliage  upon  the  other. 
Appearance:  Spongy,  brown,  even  blackish.  Cut 
surface:  Salmon-red,  foliated.  Nature  and  quantity 
of  impurities :  Many  particles  of  bark;  45  per  cent. 
Valuation:  Very  hard,  very  nervy,  rapidly  cooling 
gutta.  Nature  of  the  thread :  Wrinkly. 

Kotaringin.  Origin:  South  Borneo.  Form: 
Spindles  pointed  on  both  ends,  the  cross-section  of 
which  is  square  or  oblate,  and  which  weigh  2  to  4 
Ibs.  Also  parallelepipeds  rounded  off  and  reduced 
on  the  ends  and  weighing  0  to  8  Ibs.  Appearance: 
Paler  than  the  preceding.  Cut  surface:  Salmon- 
red,  foliated.  Quantity  of  impurities:  32  per  cent. 
Valuation:  Somewhat  less  nervy  than  Banjer-mas- 
sin. Nature  of  the  thread :  Wrinkly. 

Pekang.  Origin:  In  Pekang  on  the  sea-coast. 
Form:  Loaves  1J  to  If  inches  thick  and  weighing 
4  to  11  Ibs.  Appearance:  Brown-reddish,  dark 
plume-color,  mouldy.  Cut  surface:  Wine-red,  very 
homogeneous.  Nature  and  quantity  of  impurities : 
23  per  cent.  Valuation:  Not  very  hard  or  nervy; 
cools  with  difficulty.  Nature  of  the  thread:  Smooth. 
Sarawak.  Origin :  Northwestern  part  of  Borneo. 


RAW    MATERIAL.  239 

Form :  The  loaves,  when  dry,  are  light  in  propor- 
tion to  their  size.  Appearance  :  Spongy  loaves  ;  the 
surface  is  warty  with  earth-brown  bark.  Cut  sur- 
face:  Yellow-reddish  with  white  veins.  Nature  and 
quantity  of  impurities :  Many  particles  of  bark  ;  50 
per  cent.  Valuation :  Very  good  quality ;  very 
nervy ;  cools  rapidly.  Nature  of  the  thread  : 
Wrinkly. 

PontianaL  Origin :  Southwestern  portion  of 
Borneo.  Form:  Blocks  weighing  11  to  22  Ibs. 
Appearance :  Very  spongy,  yellow-reddish,  grayer 
than  Sarawak.  Cut  surface:  Like  Sarawak,  gray 
or  with  white  veins.  Nature  and  quantity  of  impur- 
ities :  Many  impurities ;  44  per  cent.  Valuation  : 
Very  good  gutta.  Nature  of  the  thread  :  Wrinkly. 

Pedang.  Origin:  West  Sumatra.  Form:  Flat 
parallelopipeds  weighing  about  4  Ibs.  each.  Each 
of  them  bears  the  stamp  of  its  origin.  Also  larger 
loaves  weighing  up  to  G6  Ibs.  Appearance:  Very 
pronounced  yellow-reddish.  Cut  surface:  Like  the 
outside;  perceptibly  foliated.  Nature  and  quantity 
of  impurities  :  Many  impurities  ;  40  per  cent.  Val- 
uation :  Hard  and  nervy  ;  cools  rapidly.  Nature  of 
the  thread :  Nervy.  This  gutta-percha  cannot  be 
used  unmixed  for  electrical  purposes. 

Sarapong  or  Souni.  Origin :  East  Sumatra. 
Form :  Oval  loaves  running  to  a  point  on  both 
ends,  and  weighing  from  1  to  2  Ibs.  Appearance  : 
Surface  wrinkly,  earthy.  Cut  surface:  Homogene- 
ous, white-yellowish.  Nature  and  quantity  of  impur- 
ities :  Very  pure  ;  30  per  cent.  Valuation  :  Inferior 


240        INDIA    RUBBER,  GUTTA    PERCHA,  BALATA. 

quality  ;  quite  hard  but  not  very  nervy  ;  cools  well. 
Nature  of  the  thread :  Very  smooth. 

The  term  Souni  is  applied  to  a  series  of  mixtures 
prepared  by  the  natives  of  Sumatra,  which  contain 
white  and  red  gutta  in  varying  quantities.  Selig- 
mann-Lui  saw  the  following  mixture  prepared : 
Gutta  Derriam  (Dichopsis  oblongifoUum)  2  parts, 
Sundeck  (Payena  Lerii)  3  parts,  Pontch  (Boula- 
Balam)  1  part.  Sarapong  is  a  type  of  a  good  mix- 
ture suitable  for  telegraph  wires. 

Siak.  Origin:  East  Sumatra.  Form:  Clubs 
thicker  in  the  centre  and  weighing  from  4  to  7  Ibs. 
Appearance:  Yellow-reddish.  Cut  surface:  Paler, 
foliated.  Nature  and  quantity  of  impurities :  Very 
much  bark  ;  50  per  cent.  Valuation :  Quite  hard 
but  not  very  nervy  ;  cools  quite  well.  Rain-re  of 
the  thread  :  Very  smooth. 

Bolungan.  Origin  :  East  Borneo.  Form  :  Clubs 
provided  on  top  with  a  loop  which  is  formed  by 
folding  the  thinner  portion  of  the  club  upon  the 
thicker,  and  several  times  twisting  this  end.  The 
best  quality  comes  in  small  loaves  weighing  4  to  10 
Ibs.,  also  larger  loaves  weighing  up  to  GO  Ibs.  Ap- 
pearance :  Blackish,  almost  sooty;  knotty.  Ont  sur- 
face: White  or  violet  color;  foliated.  A  jnice 
exudes  which,  on  exposure  to  the  air,  immediately 
hardens  upon  the  knife.  Nature  and  quantity  of 
impurities:  Very  pure,  but  adulterated  with  pieces 
of  bark  all  of  the  same  shape  and  very  likely  ob- 
tained from  the  tree  producing  the  gutta.  Valua- 
tion :  Hard,  nervy  ;  cools  well.  Nature  of  the  thread : 
Wrinkly. 


RAW    MATERIAL.  241 

Coti.  Origin :  East  Borneo.  Form :  Pieces  of 
even  size.  Rolls  32  inches  long  and  5|  inches  in 
diameter.  They  are  formed  of  thin  leaves  rolled 
up  ;  the  ends  have  been  turned  back  with  the  hand 
and  show  the  imprint  of  the  fingers  which  have 
kneaded  the  gutta.  Appearance:  Like  covered  with 
a  net.  The  meshes  of  the  net  are  filled  with  yellow 
or  yellow-reddish  particles  of  wood.  Many  pieces 
bear  a  stamp  and  are  then  mostly  somewhat  reddish. 
Cut  surface :  Perceptibly  foliated,  white-yellowish  or 
grayish,  and  like  Bolungan  separates  a  viscous 
liquid.  The  cut  surface  of  the  stamped  pieces  is 
more  reddish.  Nature  and  quantity  of  impurities  : 
But  little  bark  ;  30  per  cent.  The  stamped  pieces 
contain  more  bark.  Valuation:  Hard,  quite  nervy, 
cools  well.  The  stamped  pieces  are  of  better  quality. 
Nature  of  tlie  thread  :  Quite  smooth. 

Cotonan.  Origin  :  Unknown.  Form  :  Small,  flat 
loaves  weighing  4  to  6J  Ibs.  Appearance:  Surface 
very  smooth.  Cut  surface:  Very  white;  separates  a 
viscous  fluid..  Nature  and  quantity  of  impurities: 
Little  or  no  bark,  but  much  water;  30  per  cent. 
Valuation  :  Hard,  but  not  nervy  ;  cools  well.  Nature 
of  the  thread:  Very  smooth.  The  separated  fluid 
smells  like  rotten  cheese.  Loss  in  washing,  30  per 
cent.,  of  which  only  2  per  cent,  is  solid  constituents. 

Kclatan.  Origin  :  Northeastern  part  of  the  penin- 
sula Malacca  in  the  northern  portion  of  Pahang. 
Form:  Balls  of  thread  analogous  to  the  African 
rubber  balls  and  weighing  1  to  2  Ibs.  Appearance: 
In  a  fresh  state  rose-color  and  wax-like  ;  when  older, 
16 


242    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

chalk-white.  Cut  surface:  Very  white,  separates  a 
viscous  fluid.  Quantity  of  impurities:  30  per  cent. 
Valuation :  Very  friable  ;  on  the  whole  not  very 
hard ;  does  not  cool  well.  Nature  of  the  thread  : 
Very  smooth. 

Under  this  name  two  kinds  of  gutta  percha  are 
known.  On  examining  the  one  kind,  it  is  plainly 
seen  that  it  is  just  as  it  has  been  collected.  This  is 
known  as  gutta  vierge.  The  second  kind  consists 
of  two  parts,  a  core  of  inferior  quality  coated  with  a 
layer  of  better  quality.  This  variety  becomes  brittle 
in  a  short  time. 

Pahang-white.  Origin:  Pahang.  Form:  Balls  of 
a  size  larger  than  a  head.  Appearance :  Chalk-white. 
Cut  surf  ace  :  Friable.  Quantity  of  impurities  :  40  per 
cent.  Valuation :  Quite  nervy,  viscous  ;  cools  well. 
Nature  of  the  thread :  Very  smooth,  but  difficult  to 
work  by  itself,  as  it  sticks  to  the  cylinder.  The  sur- 
face of  this  variety  frequently  consists  of  a  layer  of 
nervy  gutta  only  a  few  millimeters  thick.  Smells 
of  fresh  cheese. 

Assahan.  Origin :  Northeastern  part  of  Sumatra. 
Form,  Appearance  and  Cut  surface:  Same  as  Pahang- 
white.  Quantity  of  impurities  :  20  per  cent.  Valua- 
tion: Somewhat  inferior  in  quality  to  Pahang- 
white,  it  being  more  viscous  and  does  not  cool  as 
well.  Nature  of  the  thread :  Same  as  Pahang-white. 

Tringanon.  Origin:  Northeastern  part  of  the 
Malay  Peninsula  on  the  shores  of  the  Kelatan. 
Form,  Appearance,  Cut  surface:  Same  as  the  pre- 
ceding. Quantity  of  impurities :  31  percent.  Valu- 


RAW    MATERIAL.  243 

ation  and  Nature  of  the  thread:  Same  as  the  pre- 
ceding. 

Boida-Balam.  Origin:  Malacca.  Form:  Shape- 
less pieces  which  must  be  quickly  pressed  into 
blocks  as  otherwise  they  crumble  to  dust.  Appear- 
ance :  Chalk-white.  Cut  surface :  Friable.  Quantity 
of  impurities  :  31  percent.  Valuation:  A  soft  gutta 
without  nerve.  The  pieces  stick  together  even  after 
cooling  for  several  days.  To  prevent  them  from 
forming  a  mass  they  must  be  dusted  with  talc 
powder. 

The  tree  producing  this  gutta  grows  in  the  marshy 
regions  of  the  gutta-percha  countries.  Nearly  all 
varieties  of  gutta  are  adulterated  with  this  quality. 
Notwithstanding  its  low  price,  but  little  of  it  is 
used,  which  is  very  likely  due  to  the  fact  that 
enough  of  it  is  contained  in  the  white  gutta  by  the 
addition  of  which  the  working  of  the  good  brands 
is  only  rendered  possible. 

Statistics.  As  previously  mentioned,  Singapore  is 
the  principal  and  almost  exclusive  market  for  the  ex- 
port of  crude  gutta  percha.  From  statements  taken 
from  the  Straits  Settlement  Government  Gazette 
and  the  Blue  Books,  and  from  the  statistical  reports 
of  the  British  Custom  House,  Dr.  E.  Obach  calcu- 
lates the  quantity  of  crude  gutta  percha  brought  to 
Singapore  for  the  years  1885  to  1896,  as  542,081 
cwts.,  valued  at  £3,547,787,  which  gives  an  average 
price  of  14  pence  per  pound.  According  to  the 
same  sources,  the  export  of  crude  gutta  percha  from 
Singapore  from  1885  to  1896,  inclusive,  amounted 


244    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

to  619,377  cwts.,  valued  at  £4,855,794,  which  shows 
that  the  export  during  that  time  was  77,296  cvv7ts., 
valued  at  £1,308,007  greater  than  the  receipts- 
Hence  this  excess  must  have  been  taken  from  stock 
on  hand  prior  to  1885.  According  to  the  quan- 
tities shipped  direct  from  Singapore,  the  countries 
into  which  the  product  was  imported  may  be  ar- 
ranged as  follows : 

England  ....  470,770  cwts., 

France     ....  54,215  cwts., 

Germany.         .         .         .  47,151  cwts., 

United  States   .         .         .  37,894  cwts., 

Asia.         .         .         .         .  4,241  cwts., 

Holland  ....  4,202  cwts., 

Italy         ....  895  cwts., 


Total         .  .     619,377  cwts. 

This  shows  that  of  the  total  amount  exported 
from  Singapore  more  than  two-thirds  went  to 
England. 

The  re-export  from  England  amounted  in 


1885  to    9,666  cwts., 

1886  to  11, 528  cwts., 

1887  to    8,824  cwts., 

1888  to    8,373  cwts., 

1889  to    8, 304  cwts., 

1890  to  11,456  cwts., 


1891  to    6,408* cwts., 

1892  to    7,989  cwts., 

1893  to    7,430  cwts., 

1894  to    9,975  cwts., 

1895  to  12,536  cwts., 

1896  to  14,497  cwts. 


Hence,  not  quite  theee-fourths  of  the  total  impor- 
tation remained  in  the  country  for  home  consump- 
tion, and  in  stock. 


RAW    MATERIAL.  245 

From  the  English  re-export 

Germany  received  about.  48,100  cwts., 
France  received  about  .  26,000  cwts., 
Holland  received  about  .  16. 400  cwts., 
United  States  received  about  11, 500  cwts., 
Other  industrial  countries  re- 
ceived about  .  .  11, 300  cwts., 
English  colonies  .  .  3,700  cwts. 

The  principal  markets  for  gutta  percha  in  Europe 
are  Liverpool,  London,  Marseilles,  Rotterdam  and 
Hamburg. 


CHAPTER  IX. 

CHEMICAL  AND  PHYSICAL  PROPERTIES  OF  GUTTA 
PERCHA. 

IN  view  of  the  diversity  of  its  origin  and  the  rare 
occurrence  of  a  pure,  unmixed  commercial  article, 
i.  e.,  such  as  is  derived  from  one  and  the  same 
plant,  it  is  impossible  to  determine  the  physical, 
and  still  less  so  the  chemical,  properties  of  gutta 
perch  a  as  absolutely  pertinent  to  all  cases.  The 
following  statements  are  based  upon  observations 
and  experiments  made  in  the  best  markets,  and, 
generally  speaking,  may  be  considered  correct. 

Pure  gutta  percha  is  colorless  and  in  thin  sections 
transparent.  If  a  thin  slice,  about  I  millimeter 
thick,  is  laid  upon  a  white  support,  it  shows,  how- 
ever, a  specific  coloration  between  rose  color  and 
gray-white.  It  is  tasteless  and  odorless,  and  a 
characteristic  pungent  odor  occasionally  evolved  by 
it,  is  due  to  decomposition.  It  is  of  a  cellular  struc- 
ture, but  when  vigorously  stretched  it  becomes 
fibrous.  In  this  condition  it  is  very  strong  in  the 
direction  of  the  pull,  but  its  strength  decreases  in 
the  crosswise  direction,  and  it  breaks  readily  when 
pulled  that  way.  At  the  ordinary  temperature 
separate  pieces  do  not  unite,  but  when  their  surfaces 
are  slightly  heated  and  pressed  together,  they  com- 
(246) 


CHEMICAL    AND    PHYSICAL    PROPERTIES.         247 

bine   to  one  piece,  the   original    separate  parts  of 
which  cannot  be  restored. 

At  the  ordinary  temperature  gutta  percha  is  com- 
pact, pliant,  very  tough,  but  shows  little  elasticity. 
It  can  without  injury  be  folded,  knotted  and 
extended,  and  is  readily  coin  minuted  with  pointed 
or  cutting  tools.  In  elasticity  it  resembles  soft 
leather.  Its  specific  gravity  is  generally  given  as 
from  0.909  to  0.976,  but  it  is  actually  specifically 
heavier  than  water.  Thin  lamillae  of  it  laid  upon 
water  and  placed  under  the  receiver  of  an  air 
pump,  sink  as  soon  as  the  air  is  exhausted,  the 
numerous  small  pores  having  absorbed  water. 
Pa  yen,  on  stretching  gutta  percha  under  strong 
pressure  and  immediately  cutting  the  strips  thus 
produced  into  very  small  pieces  under  water,  found 
that  the  greater  part  of  the  fragments  fell  to  the 
bottom  of  the  vessel,  some  immediately,  others  after 
absorbing  a  certain  quantity  of  water. 

The  pliability  of  gutta  percha  increases  rapidly 
at  between  76°  and  86°  F.,  and  at  122°  F.  it  yields 
readily  to  slight  pressure.  At  194°  F.  it  becomes 
plastic  so  that  it  can  be  kneaded,  and  brought  into 
any  desired  shape,  which  it  retains  unaltered  when 
brought  back  to  the  ordinary  temperature.  If  care- 
fully heated  to  248°  F.  it  melts,  and  if  still  further 
heated  it  boils  up  and  yields  a  colorless  oil.  It  is 
inflammable  at  a  certain  temperature,  and  burns 
with  a  bright  flame  and  leaves  behind  a  black 
residue. 

Towards  cold,  gutta  percha  is  less  sensitive  than 


248    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

rubber,  it  suffering  no  alteration  at  14°  F.  Cold 
water  has  no  effect  upon  it,  except,  as  previously 
mentioned,  that  its  exterior  pores  absorb  a  small 
quantity  of  it. 

Examined  in  thin  sections  under  the  microscope 
it  seems  to  possess  a  porous  structure.  Rubber 
under  these  conditions  shows  little  or  no  change  of 
color,  while  gutta  percha  exhibits  a  beautiful  spec- 
tacle. It  appears  to  be  built  up  of  prisms  of  every 
variety  of  hue.  Prof.  Page  states  that  it  resembles 
more  nearly  some  specimens  of  ice  which  he  has 
examined,  than  anything  else.  The  porous  struc- 
ture ma}7  be  observed  by  allowing  a  drop  of  solution 
in  carbon  disulphide  to  evaporate  spontaneously  on 
a  glass  slide.  The  solution  is  soon  reduced  to  a 
whitish  film  and  the  numerous  cavities  with  which 
it  is  pierced  may  be  distinctly  perceived.  These 
cavities  may  be  made  more  visible  by  means  of  a 
drop  of  water;  the  liquid  gradually  insinuates 
itself,  the  mass  appears  more  opaque  and  the 
cavities  are  seen  to  be  enlarged. 

Gutta  percha  is  a  bad  conductor  of  heat  and  a 
worse  conductor  of  electricity.  When  vigorously 
rubbed  it  becomes  itself  electric,  and  when  rubbed 
with  silk  throws  out  electric- sparks.  As  regards 
resistance  to  the  electric  current,  no  other  plastic 
material  is  even  approximately  equal  to  it,  and  it 
retains  this  property  unaltered  in  the  ground  or  in 
water. 

Towards  most  solvents  gutta  percha  is  entirely 
indifferent,  Jn  cold  water  it  is  entirely  insoluble, 


CHEMICAL    AND    PHYSICAL    PROPERTIES.         249 

and  while  it  becomes  soft  in  boiling  water  or  in 
steam,  it  is  thereby  not  changed  in  any  respect. 
In  cold  weak  alcohol  it  is  almost  insoluble,  but  in 
stronger  alcohol  its  solubility  increases  and  the 
more  so  the  higher  the  temperature  becomes,  it 
losing,  in  boiling  absolute  alcohol,  15  to  20  per  cent. 
of  its  constituents.  It  is  partly  soluble  in  oil  of 
turpentine,  olive  oil  and  a  few  mineral  oils,  and 
more  soluble  in  bezene.  The  best  solvents  for  it 
are  carbon  di sulphide  and  chloroform. 

According  to  analysis  gutta  percha  consists  of  a 
combination  of  hydrocarbons,  the  composition  of 
which  resembles  very  much  those  of  rubber.  The 
oxygen  which  is  found  in  it  very  likely  belongs  to 
a  foreign  combination.  Gutta  percha  contains: — 

Carbon  .      ^^=-=^.  •          •      86-36 

Hydrogen     X0sf^P*^\      -     12.15 
Oxyo-en        f—        ERSITY)  L49 


100.00 

As  far  as  the  chemical  composition  of  gutta 
percha  is  concerned,  it  must  not  be  considered  as  a 
single  combination,  but  as  a  mixture  of  several 
bodies  which  occur  in  different  quantities  in  differ- 
ent varieties  of  it.  Two  of  these  combinations  can 
be  dissolved  by  boiling  in  anhydrous  alcohol,  and 
if  the  solution  is  allowed  to  stand  quietly  for  some 
time,  small  white  grains  are  separated,  the  surface 
of  which  consists  of  numerous  small  crystals,  but 
contain  a  yellow,  amorphous  core  in  the  centre. 
The  yellow  non-crystalline  mass  can  be  more 


250    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

easily  dissolved  in  cold  alcohol  than  the  crystals, 
and  according  to  this,  gutta  percha,  by  a  suitable 
treatment,  can  be  separated  into  three  parts,  one  of 
which  (gutta)  'is  insoluble  in  alcohol,  the  next 
(albane)  is  difficult  to  dissolve,  while  the  third 
(fluavile)  is  easily  dissolved. 

Payen,  who  thoroughly  examined  gutta  percha, 
found  in  100  parts  of  it : 

Per  cent. 
Gutta         .         .         .         .         .    78  to  82 

Albane 16  to  14 

Fluavile 6  to    4 

Pure  gutta,  which  remains  after  the  crude  gutta 
percha  has  been  thoroughly  exhausted  with  alcohol, 
is  a  white  mass,  which,  when  rolled  into  thin  sheets, 
is  tenacious  and  ductile  at  a  temperature  of  from 
59°  to  86°  F.,  but  not  very  elastic.  It  becomes  soft 
when  heated  to  113°  F.  and  assumes  a  yellowish 
color ;  the  higher  the  temperature  the  darker  and 
more  transparent  becomes  the  mass,  and  finally  be- 
comes dough-like  but  without  actually  melting.  It 
melts  when  the  temperature  is  raised  to  248°  F.,  and 
commences  to  decompose  at  a  still  higher  tempera- 
ture. Towards  solvents  its  behavior  is  the  same  as 
that  of  gutta  percha. 

Albane  is  the  crystalline  resin  which  is  separated 
from  the  solution  in  boiling  alcohol.  It  melts  at 
from  347°  to  356°  F.  If  exposed  to  a  still  greater 
heat  it  is  decomposed  and  furnishes  the  same  pro- 
ducts as  gutta. 
...fluavile. .is  a  non-crystalline  resin  of  an  orange 


CHEMICAL    AND    PHYSICAL    PROPERTIES.         251 

color.  It  is  hard  at  an  ordinary  temperature,  but 
becomes  soft  when  taken  in  the  hand,  melts  between 
212°  and  230°  F.,  and  is  decomposed  when  heated 
still  more,  emitting  at  the  same  time  pungent 
vapors. 

Recent  investigations  have  clearly  established  the 
relation  between  gutta,  albane  and  fluavile.  Ac- 
cording to  these  investigations  it  may  be  supposed 
that  the  body  which  is  of  actual  industrial  value, 
namely,  the  pure  gutta,  is  a  hydrocarbon,  being 
composed,  according  to  Baumhauer,  of  C20H32.  If 
we  compare  the  formula  for  the  composition  of  pure 
rubber  (C6H 5),  established  by  Williams,  with  that 
of  gutta,  it  will  be  seen  that  the  formula  of  the 
latter  is  equal  to  four  times  that  of  the  first,  and 
that,  therefore,  the  two  bodies  show  great  similarity 
in  regard  to  their  chemical  constitution. 

Besides  gutta  (C20H32),  according  to  Baumhauer's 
investigation,  two  more  combinations  are  found  in 
the  crude  gutta  percha.  These  are  composed  of 
C2 0^820  and  C20H3202,  and  are,  therefore,  pro- 
ducts of  oxidation  of  gutta.  We  might  suppose 
that  these  products  were  already  present  in  the 
fresh  milky  juice  itself,  but  from  the  fact  that,  if 
gutta  percha  is  stored  for  any  length  of  time,  its 
properties  undergo  an  essential  change,  we  must 
conclude  that  new  products  of  oxidation  are  con- 
stantly formed. 

Mr.  Clark  carried  out  a  series  of  experiments 
upon  gutta  percha,  and  below  the  results  as  inter- 
preted by  W.  A.  Miller  are"given  : 


252    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

500  grains  of  a  thin  sheet  of  gutta  percha  were 
exposed  for  eight  months  under  the  following  con- 
ditions : 

1.  In  netting  open  to  the  air  and  light,  but  ex- 
cluded from  rain. 

2.  In  a  bottle  open  to   the  air  and  light,  but  ex- 
cluded from  rain. 

3.  In  a  bottle  open  to  the  air,  but  excluded  from 
light. 

4.  In  fresh  water,  open  to  air  and  light. 

5.  In  fresh  water,  open  to  air,  but  excluded  from 
light. 

6.  In  fresh  water,  excluded  from  air  and  light. 

7.  In  sea  water,  exposed  to  air  and  light. 

8.  In  sea  water,  excluded  from  light,  but  exposed 
to  air. 

9.  In  sea  water,  excluded  from  light  and  air. 
The  specimens  4,  5,  G,  7,  8  and  9  were  wholly 

unaltered,  with  the  exception  of  a  slight  increase  in 
weight,  due  to  the  absorption  of  water,  which  they 
lost  again  after  exposure  to  the  air  for  one  or  two 
hours.  The  tenacity  and  structure  of  the  material 
did  not  appear  to  have  undergone  the  slightest 
change. 

No.  2,  which  had  been  folded  up  and  introduced 
into  a  bottle,  the  mouth  of  which  was  open  and  in- 
verted, had  absorbed  5  per  cent,  of  oxygen,  55  per 
cent,  of  the  mass  being  converted  into  resin.  The 
outer  layers,  exposed  to  light,  were  brittle  and 
resinous,  but  the  inner  portions,  screened  from  light 
by  the  outer  folds,  were  but  little  altered  in  texture 
or  appearance. 


CHEMICAL    AND    PHYSICAL    PROPERTIES.         253 

No.  3  bad  experienced  little  or  no  change,  had  in- 
creased in  weight  only  0.5  per  cent.,  and  yielded  to 
alcohol  only  7.4  per  cent,  of  resinous  matter. 

Another  sample  which  had  been  exposed  to  the 
light  of  day  for  a  period  of  only  two  months,  had 
become  quite  brittle,  had  increased  in  weight  3.6 
per  cent.,  and  yielded  21.5  per  cent,  of  resinous 
matter  to  alcohol,  while  a  piece  of  the  same  sheet, 
kept  in  the  dark,  had  undergone  no  sensible 
change. 

Miller  also  examined  several  specimens  of  cables 
which  had  been  submerged  for  periods  of  time  vary- 
ing from  a  few  weeks  to  seven  years.  In,  no  case 
ivhere  the  cable  had  been  completely  and  continuously 
submerged,  did  lie  find  any  sensible  deterioration  in  the 
quality  of  the  gutta  percha.  The  only  perceptible 
chemical  difference  in  the  various  specimens  was  in 
the  quantity  of  water  mechanically  retained  in  each. 

One  of  the  principal  properties  of  gutta  percha  is 
its  great  chemical  indifference.  Concentrated  alka- 
line solutions  as  well  as  not  too  concentrated  acids, 
and  all  saline  solutions,  do  not  affect  it  in  the  least. 
It  only  commences  to  char  when  subjected  for  a 
long  time  to  the  influence  of  concentrated  sulphuric 
acid  ;  but  fuming  sulphuric  acid  brings  about  a 
quicker  change,  and  transforms  it  into  a  slimy 
substance. 

Even  the  strongest  hydrochloric  acid  seems  to 
have  but  little  effect  upon  it ;  the  only  effect 
observed,  after  lying  for  months  in  the  acid,  being 
that  it  had  lost  some  of  its  pliability.  But  cold 


254        INDIA    RUBBER,  GTJTTA    PERCHA,  BALATA. 

concentrated  nitric  acid  acts  very  energetically  upon 
it,  and,  when  boiled,  dissolves  it  completely  under 
the  emission  of  red  vapors. 

Its  chemical  indifference  and  great  plasticity 
make  this  body  absolutely  invaluable  for  certain 
branches  of  chemical  industry.  As  it  is  entirely 
indifferent  towards  hydrochloric  acid,  it  is  used  for 
manufacturing  hose  for  drawing  the  acid  from  the 
vessels  containing  it,  and  is  even  employed  for 
lining  boxes  in  which  the  acid  is  to  be  transported. 

It  is  also  indifferent  towards  not  too  concentrated 
hydrofluoric  acid,  and  is,  therefore,  employed  for 
manufacturing  vats  which  are  to  be  used  in  etching 
glass,  and,  also,  bottles  in  which  the  acid  is  to  be 
kept. 


CHAPTER  X. 

TREATMENT  OF  CRUDE  GUTTA  PERCH A. 

PREVIOUS  to  actual  use  for  manufacturing,  crude 
gutta  percha,  as  brought  into  commerce,  must  be 
subjected  to  a  series  of  preparatory  manipulations, 
the  chief  object  of  which  is  the  removal  of  foreign 
constituents,  such  as  sand,  earth,  wood,  bark  and 
other  impurities.  Various  methods  are  employed 
for  this  preparatory  work,  all  of  which  are  quite 
simple. 

Before  commencing  the  treatment  of  the  crude 
material,  it  is  best  to  more  closely  examine  its  con- 
dition. This  is  done  by  taking  at  random  a  few 
pieces  from  the  mass  to  be  tested  and  catting  them 
up  with  a  knife.  If  it  is  found  that  the  impurities 
consist  only  of  pieces  of  wood,  bark  and  earth,  the 
gutta  percha  can  be  at  once  brought  into  the  cutting 
machine.  But  if  it  is  found  to  contain  stones,  it 
should  be  subjected  to  a  special  operation  before  it 
is  cut  up,  since  if  this  precaution  is  neglected,  not 
only  the  cutting  machine  might  be  ruined,  but  ac- 
cidents might  also  happen. 

For  the  purpose   of  removing  stones,  the  gutta 

percha  is  softened  in  water  of  about  122°   F.,  and 

is  then  rolled  out  into  thin  bands.     To  prevent  the 

rolls  from   being  stopped  or  injured  by  the  stones, 

(255) 


256        INDIA    RUBBER,  GUTTA    PERCH A,  BALATA. 

they  are  so  arranged  that  the  upper  one  runs  in 
movable  brasses  held  in  place  by  a  lever.  In  case 
a  stone  gets  between  the  rolls,  the  upper  one  lifts  up 
and  falls  down  again  as  soon  as  the  stone  has  passed 
through. 

By  forming  the  gutta  percha  into  bands  in  the 
above-described  manner  every  stone  can  be  immedi- 
ately detected  and  removed.  The  bands,  while  still 
warm,  are  folded  together  so  as  to  form  loose  blocks 
of  a  size  corresponding  to  the  cutting  machine. 

The  same  kind  of  machine  used  for  cutting  up 
rubber  may  also  be  employed  for  gutta  percha,  but, 
as  a  general  rule,  machines  of  special  construction 
are  provided  for  the  purpose.  Among  these  the 
drum  slicing  machine  and  the  wheel  slicing  machine 
deserve  special  notice. 

The  drum  slicing  machine  consists  of  two  circular 
disks  made  to  revolve  as  quickly  as  possible  by  a 
pulley,  and  are  connected  with  each  other  by  a  large 
number  of  obliquely-set  knives  placed  upon  the  sur- 
face of  the  cylinder.  A  vertical  cylindrical  pipe  is 
placed  underneath  the  cutting  machine,  and  in  this 
is  fitted  a  piston  which  is  pressed  upwards  by  a  lever 
suitably  weighted. 

A  cube  of  gutta  percha  is  placed  in  the  vertical 
pipe  and  pushed  by  the  piston  against  the  knives  of 
the  revolving  disk,  and  cut  into  thin  slices. 

The  wheel  cutting  machine  resembles  a  straw 
cutter.  It  has  a  fly-wheel  about  (>J  feet  in  diam- 
eter, with  the  knives  fastened  to  its  spokes.  The 
wheel  makes  from  500  to  GOO  revolutions  per 


TREATMENT  OF  CRUDE  GUTTA  PERCHA.    257 

minute.  The  block  of  gutta  percha  is  placed  upon 
an  inclined  plane  and  is  fed  to  the  knives  which 
cut  it  up  in  very  thin  shavings. 

The  shavings  thus  obtained  are  placed  in  cold 
water  to  separate  the  heavy  admixtures  from  the 
gutta  percha  which  floats  on  the  surface.  The 
gutta  percha  is  then  brought  into  vats  filled  with 
hot  water,  in  which  it  remains  until  it  is  soft  and 
the  shavings  combine  to  a  plastic  mass. 

In  this  condition  the  gutta  percha  is  suitable  for 
the  manufacture  of  many  articles  for  technical  and 
other  use ;  but  for  special,  particularly  electrical, 
purposes,  a  further  very  careful  treatment  for  the 
removal  of  all  traces  of  water  and  air  bubbles 
becomes  necessary.  Gutta  percha  intended  for  in- 
sulating electric  cables  must  form  a  thoroughly 
uniform,  homogeneous  mass,  and  to  attain  this 
object  it  has  to  be  subjected  to  a  series  of  other 
manipulations. 

For  this  purpose,  it  is  first  brought  into  the 
actual  washing  machine.  This  consists  of  an  iron 
box  which  can  be  closed  by  a  lid.  In  the  interior 
of  this  box  is  a  hollow  iron  cylinder  which  contains 
an  iron  roll  with  a  star-shaped  cross  section,  Fig. 
17.  The  cylinder  is  provided  with  a  lid  through 
which  the  gutta  percha  is  introduced.  The  box 
and  cylinder  are  filled  with  water,  which  is  heated 
by  steam  directty  introduced.  If  now  the  roll  in 
the  interior  of  the  cylinder  is  set  in  motion  by  a 
transmission  on  the  outside  of  its  axis,  the  gutta 
percha  is  forced,  in  constantly  changing  form, 
17 


258    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

through  between  the  walls  of  the  cylinder  and  the 
deep  indentations  of  the  roll.  To  still  further 
increase  the  effect,  two  nose-like  rails  are  fixed  on 
the  bottom  of  the  cylinder  which  contract  the  space 
between  the  cylinder  and  roll.  The  impurities 
washed  from  the  gutta  percha  by  this  process  fall  to 

FIG.  17. 


the  bottom  of  the  cylinder  and  through  small 
apertures  reach  the  bottom  of  the  box,  from  which 
they  are  from  time  to  time  removed  through  small 
doors. 

The  gutta  percha  is  next  brought  into  the 
kneading  machine,  Fig.  18,  which  closely  resembbs 
the  washing  machine,  except  that  the  exterior  box 
is  wanting. 

In  the  interior  of  the  machine  is  a  corrugated 


TREATMENT  OF  CRUDE  GUTTA  PERCHA.    259 

roll,  the  corrugations  running  either  parallel  with 
the  axis  of  the  roll,  or  with  more  or  less  twist, 
spirally  around  it.  The  operation  of  kneading  is 
similar  to  that  of  washing,  the  water  of  course, 
being  omitted.  The  temperature  required  is  pro- 
Fig.  18. 


duced  by  the  introduction  of  steam  in  the  space 
between  the  double  walls  of  the  cylinder. 

There  are  also  kneading  machines  in  which  work 
two  horizontal  rolls  placed  one  alongside  the  other, 
either  a  corrugated  and  a  smooth  roll  being  used,  or 
two  rolls  of  the  same  kind,  with  elliptic  disks  pushed 
obliquely  over  them.  The  rolls  of  this  latter  con- 
struction are  placed  so  that  the  disks  cross  each 
other,  Fig.  19. 

From  the  kneading  machine  the  gutta  percha  is 


260    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

brought  into  a  press  or  strainer,  which  consists  of 
a  cylinder  provided  on  the  lower  end  with  several 
sieves  of  different-sized  meshes,  arranged  one  above 
the  other,  or  with  several  perforated  bottoms  with 
different-sized  holes.  The  meshes  of  the  sieves  or 
the  perforations  of  the  bottoms  diminish  in  size 
from  above  to  below,  so  that  the  uppermost  are  the 
widest  and  the  lower  ones  the  narrowest.  The 
whole  is  terminated  by  a  bottom  with  perforations 

FIG.  19. 


of  any  desired  size.  The  soft  gutta  percha  is  forced 
through  the  machine  by  an  accurately-fitting  piston. 
In  place  of  the  strainer,  ordinary  filter  presses  are 
also  used. 

By  these  various  operations  the  gutta  percha  is 
thoroughly  worked  so  that  any  water  and  air  still 
contained  in  it  are  separated,  and  a  homogeneous 
texture  is  formed.  In  order  to  be  able  to  store  the 
material  more  conveniently  for  future  use  and  at 
"he  same  time  to  have  it  in  a  more  handy  form  for 


TREATMENT    OF    CRUDE    GUTTA    PERCHA. 


261 


working,  it  is,  after  coming  from  the  kneading 
machine  or  press,  rolled  into  thinner  or  thicker 
sheets.  The  machine  used  for  this  purpose,  Fig.  20, 
consists  of  two  rolls  with  very  smooth  surfaces 
placed  either  vertically  or  obliquely  one  above  the 
other,  and  in  general  corresponds  to  the  calender 
employed  in  working  rubber.  The  mass  is  intro- 
duced from  the  front  of  the  apparatus,  and  on  leav- 
ing it  on  the  back,  is  taken  and  carried  along  by  an 
endless  cloth. 

As  in  most  cases  quite  definite  demands  regarding 

FIG.  20. 


density,  elasticity,  electric  and  other  qualities  are 
made  on  the  finished  products,  and  these  qualities 
are  seldom  or  never  found  in  the  required  degree  and 
proportion  in  a  given  kind  of  raw  material,  the 
manufacturer  must  endeavor  to  produce  them  by 
mixing  different  varieties.  Study  and  experiments 
have  led  to  good  results  in  this  respect,  but,  as  with 
rubber,  the  knowledge  thus  acquired  is  kept  secret 
by  the  various  factories. 

Gutta  percha  is  seldom  mixed  with  foreign  con- 


262    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

stituents,  and  in  factories  particular  about  quality, 
it  is  never  done,  because  by  all  such  admixtures  the 
quality  is  impaired,  which  cannot  be  justified  by  an 
eventual  cheapening  of  the  price.  For  incorporating 
the  admixtures,  the  same  machines  as  for  kneading 
are  employed. 

Like  rubber,  gutta  percha  suffers  considerable  loss 
by  washing  and  kneading,  the  percentage  varying 
very  much  according  to  origin,  quality  and  other 
conditions.  The  best  varieties  lose  as  a  rule  15  to 
20  per  cent,  in  weight,  medium  qualities,  20  to  25 
per  cent.,  and  inferior  ones,  even  as  much  as  50  per 
cent. 


CHAPTER  XL 

INDUSTRIAL  APPLICATION  OK  GUTTA  PERCHA. 

THE  further  working  of  the  cleansed  gutta  percha, 
i.  e.,  the  preparation  of  the  various  articles  for  which 
it  is  employed,  is  similar  to  the  manufacture  of 
articles  from  non-vulcanized,  mixed  and  rolled  rub- 
ber sheets.  Generally  speaking,  the  manufacture  is 
more  simple,  because  gutta  percha  is  even  more 
plastic  and  moldable  than  rubber,  and  the  seams 
can  be  readily  cemented  together. 

In  many  cases,  gutta  percha  replaces  leather,  and 
for  some  purposes  it  is  preferable  to  it.  It  is  espe- 
cially useful  for  articles  exposed  to  moisture,  damp 
cold  and  acids,  and  for  that  reason  is  employed  in 
the  form  of  hose  for  conducting  cold  water,  beer, 
vinegar,  wine  and  acids ;  for  belts  running  in  wet 
places ;  for  buckets,  ladles,  shovels,  bottles,  siphons, 
funnels  and  spigots  in  chemical  factories.  It  is 
largely  used  in  galvanoplast}^  for  the  preparation  of 
moulds  and  matrices.  It  is  also  employed  for  sur- 
gical purposes.  When  perfectly  pure  it  serves  for 
filling  hollow  teeth  and  for  the  manufacture  of  plates 
for  artificial  sets  of  teeth,  and  rolled  out  to  the  thick- 
ness of  paper  for  different  surgical  bandages  and  com- 
presses. In  the  form  of  very  thin  taffeta  it  is  used 
for  sweat  bands  in  hats  and  caps.  An  important 
(263) 


264        INDIA    RUBBER,  GUTTA    PERCHA,  BALATA. 

application  of  gutta  perch  a  is  its  use  for  coating 
quick -matches  so  that  they  can  be  carried  through 
water  without  injury  to  the  priming  composition. 
However,  the  most  important  use  of  gutta  percha  is 
as  insulating  material  for  electrical  wires,  especially 
for  submarine  and  underground  cables. 

Articles  are  moulded  from  gutta  percha  by  work- 
ing it  by  hand,  whilst  in  a  soft  and  plastic  state, 
into  the  required  form.  It  needs  very  careful, 
though  not  skilled,  labor.  To  prevent  it  sticking 
to  the  hands  or  fingers,  they  should  be  wetted  with 
water  containing  a  little  soap,  taking  care  to 
remove  all  traces  of  moisture  when  jointing  is 
required.  It  is  kept  soft  in  water  heated  by  steam. 
Picture  frames  and  similar  articles  are  made  in 
metallic  moulds. 

Gutta  percha  hose.  Special  machines  are  used  for 
manufacturing  gutta  percha  hose.  In  their  con- 
struction they  closely  resemble  presses  used  for 
manufacturing  drain  pipes  from  clay,  and  may  be 
described  as  follows : 

A  pipe,  which  determines  the  outer  diameter  of 
the  hose  to  be  manufactured,  is  fitted  in  the  centre 
of  the  bottom  of  a  strong  iron  cylinder.  A  round 
core  having  a  diameter  equal  to  the  interior  diam- 
eter of  the  hose  sticks  in  this  pipe. 

When  the  cylinder  has  been  filled  with  the 
material,  a  strongly  wrought  disk,  which  acts  as  a 
piston,  is  placed  in  it  and  pressed  slowly  forward, 
but  with  great  force,  by  a  rack  and  pinion.  To 
obtain  long  and  perfect  hose,  great  care  must  be 


INDUSTRIAL    APPLICATION.  265 

observed  in  charging  the  cylinder  with  the  gntta 
percha  softened  by  heat,  it  being  absolutely  neces- 
sary that  the  entire  space  be  filled  without  the 
occurrence  of  air  bubbles. 

To  attain  this  object  the  work  is  done  as  follows . 
The  gutta  percha  is  divided  into  small  balls  about 
the  size  of  a  fist  and  heated  ;  as  soon  as  the  mass 
has  become  sufficiently  soft  the  balls  are  placed  in 
the  cylinder,  two  men  being  required  for  this  work. 
While  one  workman  throws  the  heated  balls  into 
the  cylinder,  the  second  stamps  them  with  a  flat 
pestle  into  a  homogenous  mass.  This  labor  is  con- 
tinued until  the  cylinder  is  filled  up  so  far  as  to 
just  leave  room  enough  for  putting  the  piston  into 
position. 

After  completing  these  operations,  steam  is  ad- 
mitted into  the  steam-jacket  to  heat  the  contents  of 
the  cylinder,  which  may  have  cooled  off  somewhat 
while  putting  them  into  the  cylinder,  and  the  heat 
is  maintained  until  the  mass  is  entirely  soft.  The 
actual  work  is  commenced  when  a  small  test  proves 
that  the  gutta  percha  can  be  worked  without 
difficulty. 

The  hose  upon  leaving  the  machine  has  a  consis- 
tency not  much  greater  than  flour  dough,  and  must 
be  cooled  off  as  rapidly  as  possible  to  an  ordinary 
temperature  in  order  that  the  gutta  percha  may 
harden. 

Most  of  the  factories  pass  the  hose,  upon  its  leav- 
ing the  apparatus,  through  a  narrow  box,  from  15 
to  25  feet  long,  supplied  with  running  cold  water. 


266    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

Practical  results  have  proved  this  length  to  be 
sufficient  to  cool  off  the  hose  so  that  it  will  retain 
its  shape. 

If  hose  is  to  be  manufactured  of  such  a  length 
that  one  charge  of  the  cylinder  does  not  furnish 
sufficient  material,  the  action  of  the  piston  may  be 
stopped  when  the  material  in  the  cylinder  is  nearly 
exhausted,  and  the  latter  filled  anew.  The  mass  is 
then  heated  to  the  necessary  degree  and  the  labor 
continued.  Hose  more  than  975  feet  long  has  been 
manufactured  in  this  manner. 

Only  very  recently,  machines  have  been  con- 
structed which  permit  the  manufacture  of  hose  of 
any  desired  length.  From  the  manner  in  which 
they  work,  they  may  be  designated  as  hose-forging 
machines. 

A  section  of  hose  of  a  certain  diameter  and  sev- 
eral metres  long  is  prepared  with  the  previously- 
described  apparatus.  A  solid  core  of  a  suitable 
length  is  inserted  in  this  section,  and  both  are 
placed  in  a  press,  the  lower  half  of  which  consists 
of  a  semi-cylindrical  piece  of  metal  corresponding 
with  the  outer  diameter  of  the  hose.  The  upper 
half  of  the  press  supports  a  piece  of  the  same  form 
as  the  lower,  so  that  both  together  form  a  cylinder 
having  a  diameter  equal  to  the  outer  diameter  of 
the  hose.  The  two  halves  of  the  cylinder  are 
hollow  and  can  quickly  be  heated  by  super-heated 
steam  or  hot  air  to  the  temperature  at  which  rubber 
is  vulcanized. 

When  the  section   of  hose  has  been  sufficiently 


INDUSTRIAL    APPLICATION.  267 

heated,  the  cylinder  is  opened,  the  core  withdrawn, 
and  a  new  section  of  hose  pressed  out  from  the  first 
apparatus,  which  is  then  treated  in  the  same  man- 
ner. As  the  heating  process  always  requires  con- 
siderable time,  the  press  cylinder  may  be  refilled  in 
the  meanwhile,  and,  it  will  be  readily  understood, 
that  hose  of  any  desired  length  can  be  manufactured 
in  this  manner. 

By  a  slight  modification,  the  press  used  for  the 
manufacture  of  hose  may  also  be  employed  for  pre- 
paring solid  articles  of  gutta  percha. 

For  this  purpose,  the  front  of  the  cylinder  is  pro- 
vided with  a  pipe  to  which  is  fitted  the  open  end  of 
a  metal  mould,  the  hollow  part  of  which  corresponds 
with  the  form  the  article  is  to  have.  The  mould 
must  consist  of  several  pieces,  so  that  it  can  be  taken 
apart  and  the  contents  removed,  and,  besides,  must 
be  provided  with  an  opening  through  which  the  air 
contained  in  it  can  escape. 

In  order  to  form  articles  in  this  manner,  the 
mould  is  heated  to  from  86°  to  104°  F.,  and  then 
fastened  to  the  pipe,  and  the  softened  mass  of  gutta 
percha  is  forced  by  a  strong  pressure  of  the  piston 
through  the  pipe  into  the  mould,  this  being  contin- 
ued until  the  mass  makes  its  appearance  through 
the  air-hole.  The  mould  is  then  removed  and 
allowed  to  stand  until  the  gutta  percha  contained  in 
it  is  cooled  off  and  hard.  It  is  then  taken  apart 
and  the  small  cylinder,  which  has  been  formed  by 
the  mass  passing  into  the  air-hole,  cut  off. 

Gutta  percha  threads.     Gutta  percha  being  con- 


268    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

verted  into  a  very  plastic  mass  when  heated,  threads 
of  any  desired  dimensions  can  be  readily  prepared 
from  it,  rolls  as  well  as  presses  being  used  for  the 
purpose. 

For  pressing  threads  an  apparatus  closely  resem- 
bling the  one  used  for  round  rubber  threads  is  em- 
ployed, but  the  cylinder  into  which  the  gutta 
percha,  previously  heated  to  212°  F.,  is  brought 
must  be  surrounded  by  a  steam  jacket  to  maintain 
this  temperature  in  the  cylinder. 

To  prevent  the  operation  from  being  interrupted 
and  to  make  it  possible  to  obtain  the  gutta  percha 
in  the  form  of  coherent  threads  from  the  narrow 
tubes,  great  care  must  be  had  in  filling  the  cylinder 
so  that  the  mass  is  compact  and  contains  no  spaces 
filled  with  air,  as  this  would  cause  the  thread  to 
break.  The  simplest  way  of  avoiding  this  is  to 
bring  the  softened  gutta  percha  into  a  cylinder  of 
the  same  diameter  as  the  press-cylinder.  The  mass 
is  solidly  pressed  into  this,  and  the  cylinder  of  gutta 
percha  thus  formed,  is  then  transferred  to  the  press- 
cylinder. 

The  other  parts  of  the  apparatus  are  arranged  in 
the  same  manner  as  in  the  one  used  for  manufac- 
turing rubber  threads.  A  number  of  endless  cloths 
are  also  used,  over  which  the  threads  are  carried, 
so  that  they  may  cool  off  and  harden,  but  they 
need  not  be  as  long  as  those  used  in  the  manufac- 
ture of  rubber  threads.  The  best  plan  for  cooling 
them  off  quickly  is  to  use  a  powerful  ventilator, 
throwing  out  a  strong  current  of  cold  air.  Dusting 


INDUSTRIAL    APPLICATION.  269 

with  powdered  talc  is  superfluous,  as  gutta  percha 
loses  all  stickiness  when  cooled  off  to  a  certain 
degree.  It  is  best  to  wind  the  finished  threads 
upon  rollers  of  considerable  diameter,  as,  when  this 
is  done,  it  is,  easier  to  stretch  them  straight  again  in 
case  this  becomes  necessary. 

For  manufacturing  threads  by  rolling,  the  gutta 
percha  must  first  be  converted  into  a  band  some- 
what thicker  than  the  diameter  of  the  threads 
which  are  to  be  cut. 

The  rolls  used  for  this  purpose  are  so  constructed 
that  half  cylinders  are  cut  in  each,  and  the  grooves, 
formed  in  this  manner,  stand  so  close  together  that 
their  edges  touch  each  other  and  form  cutting  edges. 
The  rolls  are  placed  over  each  other  in  such  a  way 
that  two  grooves  fit  exactly  together  and  form  a 
circular  groove. 

The  band  to  be  cut  into  threads  is  heated  to  212° 
F.  immediately  before  it  is  passed  through  between 
the  rolls,  and  is  carried  to  them  over  a  plate  of 
polished  steel.  The  threads  are  then  cooled  off  in 
the  same  manner  as  has  been  described. 

By  using  suitably  cut  rolls  elliptic,  as  well  as 
polygonal,  threads  can  be  prepared  in  this  manner. 
The  principal  point  in  arranging  the  rolls  is  to  see 
that  the  grooves  in  the  two  rolls  fit  exactly  together, 
as  the  threads,  if  this  is  not  the  case,  will  not 
acquire  the  desired  form. 

Coating  wires  with  gutta  percha.  Of  all  the  indus- 
trial applications  of  gutta  percha,  none  is  of  greater 
importance  than  the  coating  of  wires  with  it,  as  on 


270    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

this  depends  the  establishment  of  submarine  tele- 
graph lines,  there  being  no  other  body  suitable  for 
this  purpose  which  is  such  a  non-conductor  of 
electricity.  Many  comparative  experiments  have 
proved  that  a  wire  becomes  insulatec}  by  simply 
allowing  a  coat  of  an  ordinary  gutta  perch  a  solu- 
tion to  dry  upon  it.  As  the  coating  not  only 
secures  complete  insulation,  but  also  protects  the 
wrire  against  the  action  of  sea  water,  it  may  be  said 
without  exaggeration,  that  if  gutta  percha  and  its 
properties  had  not  been  known,  submarine  telegraph 
lines  would  perhaps  never  have  been  successful. 

Insulation  of  telegraph  wires  by  coatings  of  gutta 
percha  demands  attention  to  two  very  important 
conditions  :  The  wire  must  lie  exactly  in  the  centre 
of  the  cable  or  cylinder,  and  the  covering  must  be 
perfectly  continuous,  as  the  smallest  crack  would 
allow  the  sea-water  to  enter,  and  eventually  destroy 
the  insulation. 

As  the  manufacture  of  telegraph  cables  is  a 
special  and  limited  branch  of  the  industry,  requir- 
ing large  plants,  it  has  been  thought  best  not  to 
enter  very  fully  into  the  discussion  of  the  subject, 
but  confine  ourselves  to  the  description  of  the  pro- 
cess of  coating  wire  with  gutta  percha,  large  quan- 
tities of  such  wire  being  used  in  the  manufacture  of 
electric  and  magnetic  machines. 

The  apparatus  used  for  the  purpose  consists  of  a 
cylinder  containing  the  gutta  percha  which  has  been 
softened  by  heat  and  is  pressed  forward  by  a 
piston. 


INDUSTRIAL    APPLICATION.  271 

The  soft  mass  passes  out  of  an  opening  which 
determines  the  thickness  of  the  gutta  percha  cylin- 
der. Below  this  opening  is  a  die  of  metal,  with  a 
hole  just  wide  enough  to  allow  the  wire  to  be  coated 
to  pass  through  without  much  friction. 

When  the  piston  which  acts  upon  the  softened 
material  presses  forward,  a  cylinder  of  gutta  percha 
is  pressed  out  of  the  respective  opening,  and  this,  on 
account  of  the  strong  friction,  carries  the  wire  with 
it  and  incloses  it  entirely. 

As  the  material  must  be  heated  so  far  that  it  can 
be  pressed  out  of  the  small  opening  without  the  use 
of  too  much  power,  provision  must  also  be  made  for 
sufficiently  cooling  the  mass  off  before  it  is  wound 
upon  a  drum.  All  that  is  necessary  in  this  case,  is 
to  carry  the  wire  through  a  channel  10  to  15  feet 
long,  which  is  kept  constantly  filled  with  water,  and 
then  to  wind  it  upon  a  large  drum  in  such  a 
manner  that  the  separate  windings  lie  alongside 
each  other. 

The  accompanying  illustration  (Fig.  21)  shows 
such  an  apparatus  of  the  most  simple  construction. 
C  is  a  cylinder  containing  the  softened  gutta  percha  ; 
.D  is  the  piston  by  which  it  is  pressed  forward  ;  B  is  a 
metal  cylinder  in  the  bore  of  which  the  wire  sits. 
This  is  exactly  opposite  to  the  opening,  0,  through 
which  the  gutta  percha  is  pressed.  The  wire  which 
is  to  be  covered  with  it  is  wound  loosely  upon  a 
drum,  and  is  drawn  forward  in  consequence  of  the 
high  pressure  which  the  compressed  material  exerts 
upon  it. 


272    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 


If  several  wires  coated  with  it  are  to  be  formed 
into  one  cable,  several  such  dies  of  metal  in  which 
the  wires  sit  are  fastened  to  the  cylinder  from  which 
the  gutta  percha  is  pressed.  The  wires  which  are 
to  be  formed  into  one  cable  are  passed  through  a 
cylinder  while  they  are  still  warm,  so  that  their 
coatings  adhere  to  each  other.  The  diameter  of  the 

FIG.  21. 


cylinder  should  be  such  that  the  wires,  in  passing- 
through  it,  are  gently  pressed  against  each  other. 

But  a  simple  coating  with  gutta  percha  does  not 
suffice  for  cables  which  are  to  be  immersed  in  water 
or  to  be  laid  underground.  In  such  a  case  it  serves 
only  for  insulating  the  wire.  The  cable  which  has 
been  formed  by  joining  the  insulated  wires  together 
is  generally  covered  with  Manila  hemp.  A  layer 
of  gutta  percha  is  applied  to  this  and  the  operation 
repeated  several  times. 

To  protect  the  cable  from  being  gnawed  by  ani- 
mals, it  is  covered  with  galvanized  iron  wire,  which 


INDUSTRIAL    APPLICATION.  273 

also  receives  a  coat  of  gutta  percha  to  protect  it 
against  rust.  Large  cables  are  generally  prepared 
in  such  a  manner  that  six  copper  wires  coated  with 
gutta  percha  lie  around  a  centre  wire,  which  is  also 
coated,  the  seven  wires  together  with  their  coatings 
forming  a  cylinder  having  a  diameter  of  from  0.31 
to  0.39  inch. 

However,  long  submarine  cables  must  be  still 
further  secured  against  breaking,  and  for  this  pur- 
pose are  covered  with  suitable  material — Manila 
hemp,  galvanized  iron  wire,  etc. — until  they  have  a 
diameter  of  1 J  to  1J  inches. 

Fig.  22  shows  a  machine  for  insulating  electric 
wire  and  cables,  manufactured  by  John  Royle  & 
Sons,  Paterson,  N.  J.  In  operation,  the  wire  or 
cable  enters  the  machine  at  the  back  and,  passing 
through  the  bore  of  the  thrust-bearing,  enters  the 
stock  worm,  which  is  bored  through,  the  opening 
terminating  at  the  forward  end  of  the  worm  at  a 
point  precisely  opposite  to  a  corresponding  opening 
in  the  bridge  holding  the  guider.  The  guider  is  of 
the  customary  form,  and  conducts  the  wire  to  the 
die  in  the  usual  manner.  The  guider,  when  once 
set  ready  for  operation,  is  fixed  centrally  to  the  axis 
of  the  machine,  and  cannot  be  turned  or  moved  in 
any  direction,  all  adjustments  being  made  with  the 
die,  which  is  of  compound  form,  consisting  of  a 
secondary  holder  and  a  die  of  the  usual  form,  the 
secondary  holder  being  threaded  so  as  to  screw  into 
a  die-holder  'slightly  altered  from  the  regular 
pattern.  This  arrangement  permits  of  the  die  being 
18 


274    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

adjusted  both  sideways  and  lengthwise  ;  sideways, 
by  means  of  set-screws  bearing  on  the  circumfer- 
ence of  the  die-holder ;  and  lengthwise  by  means  of 
the  secondary  holder,  which,  by  reason  of  its 

FIG.  22. 


threaded  stem,  can  be  run  backward  and  forward 
at  will.  This  method  of  adjustment  will  be  found, 
in  practice,  extremely  effective.  It  is  simple  and 
easy  of  operation,  the  adjusting  movements  being- 
directed  and  depending  merely  on  one  piece,  not  on 
a  combination  of  movements  as  heretofore. 


INDUSTRIAL    APPLICATION.  275 

In  straight-delivery  machines,  it  is  important 
that  cables,  in  passing  through,  be  prevented  from 
coining  into  contact  with  the  stock-worm,  the 
rotary  movement  of  which  might  have  a  tendency 
to  loosen  the  strands.  To  prevent  any  trouble  of 
this  sort,  the  bore  of  the  stock- worm  is  lined  with  a 
fixed  steel  tube,  which  passes  through  the  entire 
length  of  the  thrust-bearing  and  cylinder  and  ter- 
minates at  the  guider.  This  arrangement  not  only 
prevents  the  movement  of  the  stock-worm  from 
being  communicated  to  the  cable,  but  also  effect- 
ually protects  it  from  contact  with  the  insulating 
compound  before  it  reaches  the  die. 

Owing  to  the  nature  of  the  compounds  used,  in- 
sulating work  is  extremely  severe,  subjecting  the 
machine  to  heavy  strains,  the  back-thrust  being,  at 
times,  particularly  strong.  To  provide  for  all  con- 
tingencies, a  thrust-bearing  has  been  designed 
entirely  unique  in  its  application  to  machines  of  this 
character  and  possessing  features  which  fit  it  pecu- 
liarly to  this  class  of  work.  It  consists  of  a  series  of 
parallel  grooves,  extending  from  the  termination  of 
the  stock-worm  to  the  driving  gears,  into  which  is 
fitted  a  corresponding  series  of  rings,  which  surround 
the  shank  of  the  stock-worm.  The  stock-worm  ex- 
tends back  beyond  the  cylinder,  where  it  is  keyed 
into  the  inner  portion  of  this  bearing,  which,  in 
turn,  extends  back  beyond  the  driving  gear,  where 
it  terminates  in  a  bonnet  which  covers  the  end  of 
the  bearing,  and,  passing  forward  over  the  hub  of 
the  driving  gear,  serves  as  a  medium  for 


276   INDIA  RUBBER,  GUTTA  PERCH A,  BALATA. 

ting  power  from  the  driving  gear,  through  the 
thrust-bearing,  to  the  stock-worm.  Owing  to  its 
massiveness  there  is  no  danger  of  this  bearing  giv- 
ing way  under  any  pressure  that  may  be  brought  to 
bear  on  it  in  actual  service;  and,  to  prevent  heat- 
ing, carefully  selected  anti-friction  metals  are  used 
on  the  bearing  surfaces  and  ample  means  provided 
for  such  lubrication  as  may  be  necessary. 

Vulcanization  of  gutta  percha.  As  has  been  pre- 
viously mentioned,  attempts  have  been  made  to  mix 
gutta  percha  with  sulphur  and  subject  it  to  the  same 
processes  by  which  vulcanization  is  brought  about 
in  rubber.  However,  these  attempts  resulted  in 
complete  failure,  the  good  and  characteristic  quali- 
ties of  gutta  percha  being  destroyed  by  this  process, 
without  imparting  to  it  new  properties  which  would 
render  it  suitable  for  any  known  purpose.  For  the 
sake  of  completeness,  a  few  of  the  processes  recom- 
mended for  vulcanizing  gutta  percha  are  here 
given. 

A  much  smaller  quantity  of  sulphur  is  required 
for  this  purpose  than  for  rubber,  since  the  use  of  an 
excess  of  it  would  result  in  a  brittle  product.  How- 
ever, pure  sulphur  alone  is  seldom  used,  preference 
being  given  to  sulphur  in  connection  with  metallic 
sulphides,  or  to  chloride  of  sulphur.  The  following 
mixture  has  been  recommended  : 

Gutta  percha       .       .    48  parts  by  weight. 
Sulphur  .       .1  part  " 

Sulphide  of  antimony     6  parts         " 


INDUSTKIAL    APPLICATION.  277 

The  substances  are  mixed  in  a  manner  similar  to 
that  which  has  been  described  for  preparing  vul- 
canized rubber.  The  gutta  percha  is  vulcanized  at 
a  temperature  of  from  257°  to  302°  F. 

The  process  of  vulcanizing  gutta  percha  with 
chloride  of  sulphur  is  as  follows :  The  cleansed 
gutta  percha  is  cut  up  into  shreds  and  dissolved  in 
carbon  disulphide  so  as  to  form  a  stiff  solution  of 
about  the  consistency  of  syrup.  To  this  solution  2 
to  15  per  cent,  of  chloride  of  sulphur  is  added,  ac- 
cording to  the  required  extent  of  vulcanizing,  10  per 
cent,  rendering  the  gutta  percha  hard  and  horny, 
and  it  does  not  become  soft  even  if  exposed  to  a 
temperature  of  212°  F.  The  hardness  increases  in 
proportion  to  the  quantity  of  chloride  of  sulphur 
used.  Sheets  are  vulcanized  by  repeated  dipping. 
For  coating  articles  with  vulcanized  gutta  percha  a 
stiff  solution  in  carbon  disulphide  is  used.  The 
articles  are  brushed  over  with  the  solution  and,  wrhen 
dry  on  the  surface,  are  plunged  into  a  solution  con- 
taining 5  to  10  per  cent,  of  chloride  of  sulphur  to 
100  parts  of  carbon  disulphide. 


CHAPTER  XII. 

BLEACHING  OF  GUTTA  PERCHA. GUTTA  PERCHA 

COMPOUNDS. 

GUTTA  PERCHA  can  be  thoroughly  bleached  with- 
out suffering  thereby  a  chemical  change,  as  is  the 
case  with  rubber;  and  its  great  indifference  towards 
chemical  agents,  and  the  fact  that  by  bleaching  it 
loses  none  of  its  physical  and  chemical  properties, 
make  itr  an  invaluable  material  in  dentistry,  and 
the  more  so  as  a  color  can  be  given  to  it  which  so 
closely  resembles  that  of  the  human  gums  as  to  defy 
detection. 

As  bleaching  agents,  animal  charcoal  or  chloro- 
form may  be  used.  If  the  latter  is  employed,  the 
commercial  gutta  percha  is  cut  up  into  small  pieces, 
and  twenty  times  the  quantity  of  chloroform  is 
poured  over  them.  When  solution  is  complete, 
which  will  be  the  case  in  about  three  or  four  days, 
about  half  a  pint  of  water  is  added.  The  vessel 
containing  the  solution  is  then  thoroughly  shaken 
and  allowed  to  stand  quietly  until  the  contents 
have  become  separated  into  two  distinct  layers,  the 
lower  one  of  which  consists  of  a  solution  of  pure 
gutta  percha,  and  the  upper  one  of  the  water  and  the 
foreign  substances  which  had  been  mixed  with  the 
gutta  percha. 

The  clear  solution  is  then  draw  off  by  means  of  a 
(278) 


BLEACHING  OF  GUTTA  PERCHA.        279 

siphon  into  a  porcelain  basin.  This  is  placed  in  a 
copper  still  and  surrounded  with  water.  The  still 
is  then  closed  and  heated,  and  the  chloroform  dis- 
tilled off. 

The  purified  gutta  percha  remains  in  the  porce- 
lain basin  in  the  form  of  a  vesicular  mass,  which 
can  be  formed  into  plates  and  small  sticks  by  soften- 
ing it  in  hot  water  and  by  mechanical  treatment. 
AVhile  a  purified  article  is  obtained  in  this  manner, 
it  is  not  entirely  decolorized,  as  it  always  shows  a 
weak  yellowish  or  brownish  color. 

An  entirely  decolorized,  pure  white  product  may 
be  obtained  as  follows :  Purified  gutta  percha  is 
dissolved  in  twenty  times  the  quantity  of  carbon 
disulphide.  The  solution  is  clarified  by  allowing 
it  to  stand  quietly,  and  is  then  filtered  through 
finely  powdered  animal  charcoal.  But  on  account 
of  the  great  volatility  of  the  solvent,  it  is  necessary 
to  use  a  suitable  apparatus  for  filtering. 

An  apparatus  of  this  kind,  of  simple  construction, 
and  performing  excellent  service,  is  shown  in  the 
accompanying  illustration  (Fig.  23).  It  consists  of 
a  large  bottle,  F,  either  of  glass  or  tin.  This  is 
hermetically  closed  by  a  cork  with  two  holes.  The 
neck  of  the  glass  funnel,  T,  the  upper  rim  of  which 
is  ground  smooth,  is  placed  in  one  of  the  holes,  and 
a  glass  tube,  r,  bent  at  a  right  angle,  is  fitted  into 
the  second  hole.  A  thick  wooden  lid,  with  a  ring 
of  rubber  on  the  lower  side,  is  placed  upon  the 
funnel,  thus  closing  it  air-tight.  In  the  centre  of 
the  lid  is  fitted  a  glass  tube,  r',  also  bent  at  a  right 


280    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

angle,  which  is   connected  with  the  tube  r  by  a 
rubber  hose,  /•. 

The  funnel,  the  neck  of  which'  is  closed  by  a 
stopper  of  cotton,  is  filled  about  two-thirds  full  with 
animal  charcoal.  The  solution  to  be  filtered  is 
poured  upon  this,  the  lid  is  placed  in  position,  and 
must  be  removed  only  for  the  purpose  of  pouring 
more  solution  into  the  funnel.  The  air  in  the  bot- 


tle F  is  displaced  by  the  solution  dropping  into  it, 
and  escapes  through  r,  k,  and  r'  into  the  funnel  T, 
where  it  absorbs  the  vapor  of  the  solution,  but  ab- 
sorbs nothing  more  after  it  is  once  saturated.  While 
evaporation  goes  on  constantly  when  an  open  funnel 
is  used,  it  is  entirely  checked  by  using  this  appara- 
tus. To  obtain  the  last  remnant  of  the  solution  re- 
tained by  the  animal  charcoal,  a  quantity  of  carbon 


BLEACHING  OF  GUTTA  PERCHA.       281 

disulphide,  about  f  inch  deep,  is  poured  upon  the 
animal  charcoal,  which  will  remove  all  the  solution 
from  it. 

The  solution  filtered  through  animal  charcoal  is 
almost  colorless,  and  after  the  evaporation  of  the 
carbon  disulphide  an  entirely  white  mass  is  obtained 
which  can  be  colored  with  the  most  delicate  color- 
ing matter.  To  remove  the  last  traces  of  the  sol- 
vent the  mass  is  heated  for  some  time  at  212°  F. 

Solutions  of  gutta  percha  bleached  in  this  man- 
ner are  entirely  colorless,  and  when  spread  upon 
glass  plates  furnish  a  coating  resembling  a  film  of 
collodion,  but  have  the  advantage  of  possessing 
greater  solidity  and  tenacity.  As  the  preparation 
of  bleached  gutta  percha  is  rather  complicated,  it  is 
scarcely  employed  for  any  other  but  dental  pur- 
poses, although  an  excellent  use  could  be  made  of  it 
for  ivory  compositions,  though  at  present  such 
masses  can  be  prepared  more  cheaply  with  the 
assistance  of  celluloid. 

CatteWs  bleache'd  gutta  percha  is  made  by  dissolving 
cleansed  gutta  percha  in  solvents  requiring  heat,  as 
coal-tar  naphtha  and  its  rectified  products,  turpen- 
tine, and  rosin-spirit,  or  solvents  requiring  no  heat- 
ing, as  chloroform  or  carbon  disulphide.  In  using 
the  first  class  of  solvents,  1  02.  of  alcohol,  holding 
in  solution  30  drops  of  glycerine  to  the  gallon,  is 
agitated  in  a  closed  vessel,  together  withh  the  sol- 
vent and  gutta  percha,  for  an  hour  or  more,  until 
sufficiently  defecated  or  decolorized,  when  it  is 
mixed  with  a  little  alcohol  and  glycerine,  to  precip- 


282    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

itate  the  gutta  percha.  The  solvent  is  recovered  by 
distillation.  The  alcohol  or  similar  agent  removes 
the  oxidized  portions  of  the  gutta  percha,  resins, 
etc.,  and  leaves  the  pure  gutta  percha  colorless. 

The  product  thus  obtained  can  be  mixed  with 
coloring  pigments  for  the  production  of  useful  or 
ornamental  objects.  Oxide  of  zinc,  vermilion,  and 
similar  compounds  can  be  used,  but  not  compounds 
or  oxides  which  represent  a  saturated  or  high  de- 
gree of  oxidation.  Gutta  percha  by  strong  oxida- 
tion gives  rise  to  formic  acid. 

Gutta  percha  compounds.  Gutta  percha,  similar 
to  rubber,  possesses  the  capacity  of  combining  with 
a  variety  of  substances  and  on  account  of  its  soften- 
ing when  exposed  to  heat,  the  preparation  of  such 
compounds  presents  little  difficulty.  By  choosing 
suitable  substances,  compounds  resembling  leather, 
wood,  whalebone,  horn,  and  even  stone  can  be  ob- 
tained. 

Compounds  of  rubber  and  gutta  percha  are  largely 
used  in  galvanoplasty  for  the  production  of  over- 
lapping moulds  of  one  piece.  By  itself,  gutta  percha 
is  an  excellent  material  for  taking  impressions  of 
coins,  medals,  etc.,  it  being  only  necessary  to  heat  a 
sheet  of  it  until  soft,  place  the  coin  or  medal  upon 
it  and  subject  the  whole  to  strong  pressure,  leaving 
it  in  the  press  until  cold.  The  gutta  percha  sheet 
then  shows  the  negative  picture  of  the  coin  or  medal 
in  its  finest  details,  and  such  moulds  have  the  ad- 
vantage over  those  of  plaster  of  Paris  that  they  can 
be  repeatedly  used  for  making  copies. 


BLEACHING  OF  GUTTA  PERCHA.        283 

However,  for  over-lapping  matrices  or  moulds  a 
mixture  of  rubber  and  gutta  percha  has  to  be  used, 
as  besides  plasticity  when  heated,  they  must  possess 
a  high  degree  of  elasticity  so  that  when  pulled  from 
the  copied  object,  the  mould  assumes  the  same  shape 
as  when  upon  the  object. 

The  proportion  of  rubber  and  gutta  percha  best 
adapted  for  this  purpose  can  only  be  ascertained  by 
special  experiments.  A  more  elastic  (richer  in  rub- 
ber) mixture  must  be  used  for  deeply-cut  models, 
which  are  to  be  copied  (high  reliefs)  than  is  necessary 
for  copying  a  less  projecting  article  (low  relief). 
The  best  plan  for  mixing  rubber  and  gutta  percha 
into  a  homogeneous  mass  is  to  pass  sheets  of  them 
through  between  heated  rolls  revolving  at  unequal 
velocities,  to  cut  up  or  fold  up  the  sheet  thus 
formed,  to  again  pass  this  through  between  the  rolls, 
and  to  repeat  this  operation  until  an  entirely  homo- 
geneous mass  has  been  formed. 

Gutta  percha  and  rubber  compound  for  machine 
belts.  Compounds  of  rubber  and  gutta  percha  in 
suitable  proportions  combine  great  tenacity  and 
solidity  with  a  certain  degree  of  elasticity,  and  can 
therefore  be  advantageously  used  for  the  manufac- 
ture of  machine  belts.  Although  such  belts  are 
rather  expensive,  they  are  cheaper  in  the  end,  as 
they  are  almost  indestructible,  and  besides  can  be 
readily  repaired.  A  compound  very  suitable  for 
this  purpose  consists  of: 


284    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

Parts  by  weight. 
Gutta  percha    .         .         .         .     70  to  75 

Rubber 30  to  25 

Sulphide  of  antimony        .         .       5  to    4 
Sulphur   .         .  .         .       2  to    1 

To  obtain  as  intimate  a  mixture  as  possible,  it  is 
advisable  to  weigh  the  rubber  and  gutta  percha  in 
the  form  of  shavings,  to  mix  them  thoroughly  to- 
gether and  form  bands  in  the  manner  already 
described.  These  bands  should  be  rolled  until  they 
are  entirely  homogeneous,  the  sulphur  and  sulphide 
of  antimony  being  incorporated  with  them  at  the 
same  time. 

The  mass,  when  finished,  is  formed  into  a  block, 
and  this  is  passed  through  between  the  rolls  at  a 
rather  low  temperature,  and  is  gradually  changed 
into  a  band  corresponding  in  width  with  that  of  the 
belt  to  be  manufactured.  When  the  thickness  of 
this  band  nearly  approaches  that  which  the  belt  is 
to  have,  the  temperature  is  lowered  so  much  that 
the  band  can  be  forced  through  between  the  rolls 
only  at  the  expense  of  great  power,  to  make  the 
mass  as  compact  as  possible. 

The  edges  of  the  belt  are  then  trimmed,  and  it  is 
covered  on  one  side  with  a  linen  or  cotton  cloth, 
and  wrapped  loosely  round  a  wooden  roller  in 
such  a  manner  that  the  cloth  forms  a  layer  sepa- 
rating the  windings  of  the  belt  from  each  other, 
since  if  this  were  neglected  the  mass  \vould  fuse 
together  during  the  heating  process.  It  is  then 
brought  into  the  heater,  and  the  temperature, 


BLEACHING  OF  GUTTA  PERCHA.        285 

especially  for  thick  belts,  must  be  raised  to  320°  F. 
When  removed  from  the  heater,  it  is  taken  from 
the  wooden  roller,  smoothed,  and  polished  by  being 
passed  through  between  the  rolls  of  a  calender. 

Hard  -gutta  percha  compounds.  Various  admix- 
tures are  used  for  this  purpose,  they  being  nearly 
the  same  as  mentioned  for  rubber,  including  earths, 
oxides  and  finely  pulverized  minerals.  While  the 
object  of  adding  some  of  the  ingredients  is  to  give 
weight  or  color  to  the  mass,  many  have  no  other 
use  except  economy  in  making  the  necessary  bulk.. 

Whiting,  white  pipe-clay,  magnesia,  oxide  of  zinc, 
washed  barytes  or  artificially  prepared  sulphate  of 
baryta  are  used  for  white,  or  rather  yellowish 
colored  articles.  If  they  are  to  be  of  light  weight, 
it  is  advisable  to  use  magnesia  ;  for  heavy  objects, 
sulphate  of  baryta  is  the  best. 

On  account  of  the  brown  color  of  unbleached 
gutta  percha,  the  compound  prepared  with  white 
materials  will  not  show  an  entirely  white,  but 
always  a  more  or  less  yellowish-brown  color.  If  it 
is  desired  to  obtain  entirely  white  compounds, 
bleached  gutta  percha  has  to  be  used. 

Ferric  oxide  (colcothar)  can  be  used  as  a  com- 
ponent for  reddish-brown  compositions;  powdered 
pyrolusite  for  dark-brown  masses  ;  and  black  com- 
pounds may  be  prepared  by  incorporating  bone- 
black,  etc.,  with  the  gutta  percha, 

The  total  weight  of  the  added  ingredients  may  be 
greater  than  that  of  the  original  gutta  percha, 
without  destroying  its  plastic  property,  or  prevent- 


286    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

ing  its  being  moulded  into  any  desired  shape.  But 
such  compounds  will  always  show  some  degree  of 
brittleness,  and  for  this  reason  their  use  is  limited 
to  such  articles  as  are  not  to  be  exposed  to  shocks,  as 
door  handles,  escutcheons,  ornaments  for  frames,  etc. 

For  articles  exposed  to  shocks,  the  foreign  admix- 
tures must  not  amount  to  more  than  from  25  to  30 
per  cent,  of  the  weight  of  the  gutta  percha,  and 
from  such  masses  may  be  manufactured  many  of 
the  utensils  for  daily  use  which  were  formerly  con- 
structed of  leather,  tin  or  wood. 

To  hide  the  peculiar  and  not  agreeable  odor  of 
gutta  percha,  sweet  smelling  substances  should  be 
mixed  with  it ;  essential  oils  having  frequently  been 
used  for  this  purpose.  While  these  completely  dis- 
guise the  odor  of  gutta  percha,  they  possess  the  dis- 
advantage of  gradually  volatilizing.  It  is,  therefore, 
advisable  to  choose  substances  which  will  retain 
their  perfume  for  a  long  time  ;  benzoin,  tonka  beans, 
and  orris  root  can  be  recommended.  Of  benzoin, 
4  per  cent,  of  the  weight  of  the  mass  is  sufficient  to 
make  the  odor  an  agreeable  one ;  of  tonka  beans  J 
per  cent,  is  more  than  sufficient ;  if  orris  root  (the 
root  of  Iris  florentinst)  is  used,  about  10  per  cent,  will 
be  required,  as  its  perfume  is  not  very  strong.  Fine 
shavings  of  sandal  wood  or  of  American  juniper 
(Juniperus  virginiana)  may  be  used  instead  of  orris 
root. 

Compounds  of  gutta  percha  and  wood.  For  many 
years,  admixtures  of  finely  pul\7erized  cocoa-nut 
shells  have  been  used  in  gutta  percha  compounds, 


BLEACHING  OF  UUTTA  PERCHA.       287 

giving  to  them  the  properties  of  wood.  The  shells 
are  powdered  in  stamp  mills,  and  the  resulting 
powder  is  sifted  and  incorporated  with  the  gutta 
percha  in  the  usual  manner. 

But  powdered  wood  and  sawdust  of  hard  woods 
can  also  be  used  for  this  purpose.  The  sawdust  is 
ground  and  sifted  so  as  to  form  fine  flour.  It  is, 
however,  absolutely  necessary  to  thoroughly  dry  the 
powdered  wood  before  mixing  it  with  the  gutta 
percha,  and  it  may  be  further  recommended  to  coat 
the  plates,  made  from  such  compositions,  with  a 
gutta  percha  varnish. 

Compounds  of  gutta  percha  and  wood  can,  like 
wood,  be  worked  by  means  of  the  saw  and  turning 
lathe,  and  can  be  very  advantageously  used  for 
covering  wooden  articles.  But  for  the  wood  and 
composition  to  adhere  tightly  to  each  other  it  be- 
comes necessary  to  frequently  saturate  the  first  with 
linseed  oil,  before  the  compound  is  laid  on,  to  pre- 
vent it  from  absorbing  atmospheric  moisture.  If 
this  precaution  is  neglected  and  the  wood  should 
become  damp,  the  compound  would  fall  off  in  con- 
' sequence  of  the  expansion  of  the  wood. 

By  coating  two  boards  saturated  with  linseed 
oil  with  a  gutta  percha  and  wood  compound,  plac- 
ing them  cross  grained  upon  each  other  and  heating 
sufficiently  to  soften  the  gutta  percha,  and  then 
subjecting  them  to  a  heavy  pressure  until  cold,  a 
tablet  of  extraordinary  tenacity  and  resistance, 
exceeding  those  of  the  hardest  woods,  will  be 
formed. 


288    INDIA  RUBBER, GUTTA  PERCH A, BALATA. 

SoreVs  gutta  percha  compounds.  The  substitutes  for 
rubber  and  gutta  percha  which  were  introduced  by 
Sorel,  must  actually  be  considered  as  gutta  percha 
compounds,  the  gutta  percha  being  mixed  with 
pitch,  rosin,  lime,  and  potter's  clay.  The  best  of 
Sorel's  compounds  consists  of: 

Parts. 

Rosin 2 

Pitch  or  asphaltum   ....       2 
Rosin-oil   ......       8 

Slacked  lime 6 

Water        .         .  .         .         .       3 

Potter's  clay      .         .  .         .10 

Gutta  percha     .         .         .         .         .12 

The  purpose  of  the  rosin-oil  in  this  composition  is 
evidently  to  dissolve  the  pitch  and  rosin,  and  the 
admixture  of  lime  is  very  likely  for  the  purpose  of 
effecting  a  combination  between  the  acids  of  the 
rosin  and  the  lime.  The  potter's  clay  is  introduced 
into  the  composition  as  an  indifferent  substance  to 
increase  the  weight  of  the  mass,  and  can,  therefore, 
be  replaced  by  other  indifferent  substances  (chalk, 
magnesia,  colcothar,  etc.),  or  can  be  entirely  left  out. 
In  the  latter  case  a  compound  is  obtained  which,  in 
regard  to  its  properties,  approaches  that  of  pure 
gutta  percha. 

The  manner  of  preparing  the  composition  is  as 
follows:  The  rosin,  pitch,  and  rosin-oil  are  stirred 
together  in  a  boiler  until  complete  solution  has  been 
accomplished,  which  can  be  accelerated  by  heating 


BLEACHING  OF  GUTTA  PERCH  A.        289 

the  substances.  The  lime  and  water  mixed  together 
to  a  paste  are  then  added,  and  finally  the  gutta 
perch  a  and  potter's  clay,  but  the  latter  only  when 
the  gutta  percha  has  become  fluid.  More  water  is 
added  to  the  mass,  and  it  is  heated  to  the  boiling 
point  of  water,  212°  F.,  and  then  taken  from  the 
boiler. 

Even  if  the  work  is  carried  on  with  the  greatest 
care,  it  will  be  impossible  to  obtain  in  this  manner 
an  entirely  homogeneous  composition.  To  do  this, 
it  is  necessary  to  pass  the  mass  several  times 
through  between  rolls.  5  per  cent,  of  stearic  acid 
or  wax  should  be  added  to  the  composition  for  the 
purpose  of  making  it  entirely  water  proof. 

Sorel  varies  his  mixture  to  suit  different  purposes 
and  claims  that  they  can  be  substituted  for  pure 
gutta  percha ;  but  his  compositions  have  not  the 
great  tenacity  of  the  pure  material,  nor  its  indiffer- 
ence to  chemical  action,  and  cannot  be  advan- 
tageously used  for  articles  liable  to  exposure  to 
chemical  agents.  The  following  are  some  of  Sorel's 
receipts  for  manufacturing  gutta  percha  compounds  : 

I.  II.  III. 

Parts.  Parts.  Parts. 

Pitch         .         .         .8  12 
'Rosin-oil  ...       4 

Coal  tar    ...      —  12 

Slacked  lime     ..66  6 

Gutta  percha    .         .      16  16  16 

Rousseau's  solutions  of  gutta  percha  and  their  use. 
19 


290    INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

Gutta  perch  a,  to  which  linseed  oil  has  been  added, 
is  heated  in  a  suitable  vessel  over  an  open  fire. 
Linseed  oil  generally  absorbs  one-tenth  of  its  weight 
of  gutta  percha. 

When  a  white  cotton  fabric  is  dipped  into  this 
solution  it  will  be  thoroughly  penetrated  by  it,  and, 
after  it  has  become  cold,  will  be  of  a  yellowish 
color,  transparent  and  very  soft.  Such  material  can 
afterwards  be  printed  with  all  kinds  of  colors. 

Whiting,  ochre,  lampblack,  etc..  may  be  added  to 
the  solution  for  the  purpose  of  thickening  and 
coloring  it,  which  will  also  remove  the  peculiar 
odor  of  the  gutta  percha. 

For  lacquering  leather,  coating  of  taffeta  and 
gauze,  some  copal  varnish,  to  which  the  gutta 
percha  imparts  its  softness  and  elasticity,  must  be 
mixed  with  the  solution. 

It  can  be  mixed  with  all  substances — gutta 
percha  especially  exerting  no  influence  whatever 
upon  oil  paints. 

Chattertoris  gutta  percha  compound.  This  com- 
pound is  employed  for  uniting  the  different  coatings 
of  gutta  percha  cores,  and  for  cementing  gutta 
percha  to  wood,  etc.  It  is  prepared  as  follows : 
Stockholm  tar,  i  part,  by  weight,  and  about  the 
same  weight  of  rosin,  are  put  into  a  jacketed  vessel 
heated  by  steam,  strained  when  melted  and  inti- 
mately mixed  with  f  part  by  weight  of  cleansed 
gutta  percha  in  shreds  or  thin  pieces.  The  whole 
is  worked  together  by  horizontal  stirrers,  fixed  on  a 
vertical  shaft. 


CHAPTER  XIII. 

RUBBER  AND  GUTTA   PERCHA    WASTE    AND    ITS    UTILI- 
ZATION. 

THERE  will  always  be  a  certain  amount  of  waste 
in  manufacturing  articles  from  rubber  and  gutta 
percha,  no  matter  how  carefully  the  work  may  be 
done,  and  the  materials  being  expensive,  means 
should  be  found  of  turning  this  waste  to  account. 

A  distinction  must  be  made  between  waste  from 
pure  and  from  vulcanized  rubber,  and  care  should 
be  observed  to  keep  them  separate,  because  while  the 
working-up  of  one  kind  of  waste  is  quite  simple,  and 
there  is  but  little  difficulty  in  deciding  how  it  can 
be  utilized  to  the  best  advantage,  a  mixture  of  dif- 
ferent kinds  of  waste  frequently  presents  consider- 
able difficulty  in  working,  and  besides  a  mass  of 
little  value  is  finally  obtained  which  is  only  fit  for 
articles  of  very  ordinary  quality. 

The  utilization  of  pure  crude  rubber  waste  is  a 
very  simple  matter,  it  being  only  necessary  to  form  it 
into  lumps  and  to  pass  these  again  through  between 
the  rolls.  The  material  thus  obtained  frequently 
possesses  a  higher  degree  of  plasticity  than  that 
originally  used. 

Waste  of  vulcanized  rubber  is  comminuted  as 
much  as  possible  by  mechanical  means,  a  grating 
(291) 


292    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

apparatus  or  hollander  being  generally  used  for  the 
purpose,  and  then  mixed  with  pure  rubber  cut  up 
into  very  small  pieces.  The  materials  are  then 
mixed,  which  is  done  by  repeatedly  passing  the 
heated  mass  through  between  rolls,  while  at  the 
same  time  sufficient  sulphur  is  added  to  vulcanize 
the  pure  rubber  to  the  same  extent  as  the  waste. 
The  mass  must  be  worked  until  it  is  so  uniform  that 
the  separate  parts  cannot  be  distinguished  from  each 
other  by  the  naked  eye,  and  then  articles  may  be 
fashioned  from  it  in  the  usual  manner,  whicli  are 
finally  vulcanized  by  subjecting  them  to  the  heat- 
ing process. 

According  to  another  process  the  waste  is  first  cut 
up  into  small  pieces.  These  are  boiled  for  several 
hours  in  caustic  soda  for  the  purpose  of  desulphur- 
izing them.  But  this  can  only  be  done  in  a  satis- 
factory manner  when  the  pieces  are  very  small,  and 
the  boiling  is  continued  for  a  sufficiently  long  time. 

In  order  to  knead  the  waste,  after  it  has  been 
boiled,  together  with  rubber,  it  is  only  necessary  to 
continue  the  boiling  until  the  pieces  again  possess 
the  property  of  sticking  together  when  heated. 

It  is  claimed  that  by  Aco's  process,  not  only  waste 
of  ordinary  vulcanized  rubber  can  again  be  utilized 
but  also  that  of  hard  rubber.  220  pounds  of  waste 
are  treated  in  a  closed  vessel  for  two  hours  with  a 
mixture  of  22  pounds  of  carbon  disulphide,  and  495 
pounds  of  spirit  of  wine.  It  is  claimed  that  by  this 
manipulation  the  mass  becomes  sufficiently  softened 
to  allow  of  its  being  mechanically  treated  by  masti- 
cating and  kneading. 


WASTE    AND    ITS    UTILIZATION.  293 

If  this  process  could  be  used  just  as  described,  it 
would  surpass  all  others  in  regard  to  simplicity. 
But  the  results  of  many  experiments  have  always 
been  that  many  difficulties  arise  which  can  scarcely 
be  overcome,  and  especially  when  hard  rubber  is 
mixed  with  the  waste. 

If  the  work  is  to  be  done  by  this  process,  it  is  at 
least  necessary  to  sort  the  pieces  of  hard  rubber  from 
the  waste  and  to  treat  them  by  themselves.  But 
the  simplest  manner  of  utilizing  hard  rubber  waste 
is  to  melt  it  and  work  it  into  varnish,  as  described 
in  a  previous  chapter. 

Another  method  of  utilizing  vulcanized  rubber 
waste  is  as  follows :  The  waste  is  comminuted  as 
much  as  possible  and  is  then  exposed  to  a  tempera- 
ture of  572°  F.,  until  a  plastic  mass  has  been 
formed.  Heating  is  effected  by  steam  which  is 
passed  through  a  cylinder  containing  the  small 
pieces  of  waste.  Eleven  pounds  of  the  plastic  mass 
obtained  are  mixed  with  two  ounces  of  palm  oil, 
six  ounces  of  sulphur  and  two  pounds  of  white  lead 
or  magnesia,  chalk  or  oxide  of  zinc.  Articles 
moulded  from  this  mass  are  subjected  to  the  heating 
process. 

In  conclusion,  Newton's  method  may  be  men- 
tioned. The  waste  is  treated  in  a  well-closed  vessel 
with  camphene.  It  is  allowed  to  remain  in  the 
vessel  for  fourteen  days,  and  is  then  heated  to  about 
158°  F.  to  complete  the  action  of  the  camphene. 
The  greater  portion  of  the  solvent  is  then  distilled 
off,  and  the  tough  mass  remaining  in  the  still 


294    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

worked  up.  However,  if  the  vulcanized  rubber  has 
been  prepared  with  the  assistance  of  metallic  sul- 
phides, the  result  is  not  satisfactory. 

However,  no  matter  what  process  may  be  used 
for  the  production  of  rubber  mass  from  waste  of 
vulcanized  or  hard  rubber,  the  resulting  product 
never  possesses  the  properties  demanded  of  a  first- 
class  material.  It  is  therefore  best  to  work  it  into 
hard  rubber  articles,  of  course  after  it  has  been 
comminuted  in  a  suitable  manner  and  mixed  with 
pure  rubber  and  sulphur.  The  disparity  of  quality 
is  not  so  perceptible  in  these  articles  as  in  those  of 
vulcanized  rubber,  which  must  possess  a  high  de- 
gree of  elasticity  at  all  temperatures. 

Waste  of  gutta  percha  accumulating  in  the  factory 
is  more  valuable  than  that  of  rubber,  because  it 
being  as  a  rule  pure,  not  mixed  with  foreign  sub- 
stances and  not  vulcanized,  it  can  at  once  be  utilized. 
On  the  other  hand,  the  value  of  old  material  is  de- 
pendent on  the  degree  of  oxidation  it  has  undergone 
and  the  chemical  influences  to  which  it  has  been 
exposed  by  the  action  of  acids  or  very  high  tem- 
peratures. Such  old  material  is  frequently  almost 
worthless,  while,  when  it  is  only  oxidized,  it  can  be 
again  made  available  by  treatment  with  hot  water 
to  which  caustic  soda  has  been  added,  or  with  ben- 
zene or  turpentine,  by  washing,  kneading  and  mix- 
ing with  fresh  virgin  material. 


CHAPTER  XIV. 

EXAMINATION  OF  RUBBER  ARTICLES. 

VERY  few  of  the  articles  found  in  commerce  are 
made  of  pure  rubber,  most  of  them  containing 
abundant  additions  of  other  less  valuable  inorganic 
or  organic  materials,  such  as  chalk,  gypsum,  heavy 
spar,  oxides  of  zinc  and  iron,  cork  meal,  oil,  paraf- 
fine  and  similar  substances.  These  additions  are 
made  to  such  an  extent  that  many  articles  may  be 
designated  as  an  admixture  of  rubber  combined 
with  mineral  powder.  It  is  difficult  to  decide  how 
far  these  admixtures  are  to  be  considered  serviceable 
or  as  adulterations,  since  the  articles,  according  to 
the  demands  on  them,  must  consist  of  pure  material 
or  must  receive  various  additions.  Thus,  according 
to  Kissling,  a  packing  ring  for  steam  pipes  should 
have  a  different  composition  from  a  gas  tube,  or  a 
man-hole  ring  for  a  compressed  air  receiver.  A 
valve  which  has  to  resist  the  action  of  strong  min- 
eral acids  must  be  made  of  a  different  mixture  from 
a  so-called  oil-resisting  rubber  article.  However, 
there  is  still  considerable  confusion  regarding  the 
question  how  large  the  percentage  of  rubber  in  a 
technical  article  intended  for  one  or  the  other  pur- 
pose must  be. 

The  determination  of  the  specific  gravity  affords 
(.295  ) 


296        INDIA    RUBBER,  GUTTA    PERCHA,  BALATA. 

a  clue  to  the  extent  of  the  admixtures.  Since  pure 
rubber  and  pure  gutta  percha  are  specifically  lighter 
than  water,  massive  articles  of  pure  materials  will 
float  upon  water.  By  the  addition  of  the  sulphur 
required  for  vulcanizing,  the  specific  gravity  is 
somewhat  increased,  but  only  in  so  far  that  the 
articles,  if  they  contain  no  other  admixtures,  still 
float  upon  water,  or  are  only  slightly  specifically 
heavier  than  water,  while  by  the  addition  of  min- 
eral substances  the  specific  gravity  is  considerably 
increased,  as  shown  by  the  following  determina- 
tions : 

Specific  gravity.      Content  of  ash,  Quality  of 

per  cent.  gas  tubes. 

0.98  0.66\ 

0.99  2i83  I  very  good  tubes. 

1.05  2.00     ordinary  tubes. 

1.20  19.00     gray-black,  inferior  quality. 

1.17  24.60  \  gray-black,   cracks  readily, 

1.20  25.00  f      but  elastic. 

1.26  34.30     gray,  very  bad. 

1.52  38.60     red,  becomes  brittle  in  a  short 
time ;  very  bad. 

The  ash  consisted  of  zinc  oxide,  chalk  and  ferric 
oxide,  the  latter  predominating  in  the  red  tubes. 

Although  according  to  these  figures  the  specific 
gravity  alone  is  not  sufficient  for  the  determination 
of  the  quantity  of  admixtures  present,  it  throws 
enough  light  upon  the  subject  so  that  the  question 
whether  the  article  has  been  artificially  weighted  to 
a  smaller  or  greater  degree  can  be  accurately  an- 
swered, and  for  this  purpose  an  approximate  deter- 


KXAM1XATION    OF    RUBBER    ARTICLES.  297 

mimition  suffices.  This  determination  is  made  by 
placing  the  material,  cut  up  in  small  pieces,  in 
water  to  which  a  sufficient  quantity  of  a  readily 
soluble  salt  is  added  until  the  solution  has  acquired 
such  a  density  that  the  pieces  of  rubber,  when 
stirred,  neither  sink  to  the  bottom  nor  rise  to  the 
surface,  but  float  in  the  fluid  in  all  positions.  The 
fluid  then  has  the  same  density  as  the  rubber  to  be 
tested.  It  is  only  necessary  to  filter  the  fluid 
through  a  dry  filter  and  to  determine  the  specific 
gravity  of  the  filtrate  by  means  of  a  hydrometer. 

An  accurate  examination  of  rubber  articles  pre- 
sents great,  partly  insurmountable,  difficulties. 
Even  if  the  admixed  organic  substances  are  tempo- 
rarily left  out  of  consideration,  many  complications 
appear  in  the  determination  of  the  mineral  con- 
stituents. For  instance,  if  zinc  oxide  has  been  used 
as  a  filling  material,  by  ignition  a  reduction  an4 
volatilization  of  metallic  zinc  may  take  place;  sili- 
cates containing  water,  for  instance,  talc,  when 
ignited,  yield  their  water,  and  the  content  found  is 
too  small ;  the  sulphur  may  form  metallic  sulphides 
or  sulphates ;  carbonates,  white  lead,  chalk,  etc., 
yield  their  carbonic  acid  entirely  or  partly. 

For  determining  the  total  quantity  of  filling  sub- 
stances, it  is  best  to  dissolve  the  rubber  in  petroleum 
and  to  examine  the  residue,  whereby,  however,  it 
has  to  be  taken  into  consideration  that  by  this  treat- 
ment a  portion  of  the  sulphur  passes  into  solution. 

For  the  examination  of  pure  rubber,  vulcanized 
with  sulphur  alone,  the  determination  of  sulphur 


298    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

suffices  in  order  to  find  the  quantity  of  sulphur- 
present.  Unger  gives  directions  for  examining 
articles  vulcanized  with  pentasulphide  of  anti- 
mony, which  is  very  frequently  a  varying  mixture 
of  pentasulphide  of  antimony  with  free  sulphur  and 
sulphate  of  lime,  the  content  of  free  sulphur  which 
can  be  extracted  with  carbon  disulphide  amounting 
to  from  6  to  30  per  cent.,  and  that  of  sulphate  of 
lime  to  from  9  to  62  per  cent.  It  may  also  be  re- 
marked here  that  not  only  commercial  pentasul- 
phide of  antimony  contains  sulphur  which  can  be 
extracted  with  carbon  disulphide,  but  it  has  also 
been  found,  by  Wilm,  in  varying  quantities  in 
preparations  of  pentasulphide  of  antimony  made  in 
various  ways  and  with  the  greatest  care.  In  ex- 
amining such  articles  the  determination  of  the  total 
sulphur  of  the  antimony  and  calcium  must  be  taken 
jnto  consideration. 

Determination  of  sulphur.  Weigh  off  0.5  to  0.55 
gramme  of  the  sample  and  cut  it  up  into  about  100 
small  pieces.  Prepare  a  mixture  of  12  grammes  of 
finely  pulverized  cupric  oxide  and  2  grammes  of 
chemically  pure,  anhydrous  carbonate  of  soda. 
Then  place  upon  the  bottom  of  a  porcelain  crucible 
a  layer  of  pure  cupric  oxide,  and  upon  this  a  layer 
of  the  mixture.  Press  into  the  latter  about  8  pieces 
of  the  rubber  so  that  they  do  not  touch  each  other 
and  are  about  3  to  4  millimeters  from  the  sides  of 
the  crucible.  Upon  this  place  another  layer  <>(' 
mixture  and  distribute  in  it  in  the  same  manner  10 
pieces  of  rubber,  and  continue  thus  until  all  the 


EXAMINATION    OF    RUBBER    ARTICLES.  299 

rubber  has  been  brought  into  the  crucible.  Cover 
the  last  layer  slightly  with  mixture  and  pure  cupric 
oxide.  The  crucible  should  not  be  excessive!}7  large 
and  the  pieces  of  rubber  should  be  as  uniformly  as 
possible  distributed.  Cover  the  porcelain  crucible 
with  a  platinum  lid,  place  it  in  a  platinum  crucible 
and  heat  at  first  very  slowly,  whereby  the  rubber 
melts  and  penetrates  the  surrounding  mass.  Heat- 
ing is  continued  for  some  time,  but  no  gray  smoke 
should  escape,  and  only  a  peculiar  odor  reminding 
one  of  fennel  should  be  diffused.  After  moderate 
heating  for  about  half  an  hour,  the  crucible  is 
brought  to  a  red  heat  for  about  10  minutes,  when 
it  is  allowed  to  cool,  and  the  contents  are  dissolved 
in  hydrochloric  acid  with  an  addition  of  nitric  acid. 

The  fluid  is  reduced  to  dryness  in  the  water-bath 
whereby  antimonic  acid  in  an  insoluble  form  is 
separated.  The  residue  is  taken  up  with  about  600 
cubic  centimeters  of  water  and,  after  filtering,  com- 
pounded with  barium  chloride  to  precipitate  the 
sulphuric  acid,  which  is  determined  in  the  usual 
manner. 

According  to  H en riques,  correct  results  are  not 
obtained  by  fusing  with  soda  and  saltpetre,  because 
with  too  small  an  addition  of  saltpetre,  sulphur  is 
volatilized  with  the  escaping  gases,  or  with  larger 
quantities  explosions  readily  occur.  To  avoid  both, 
it  is  recommended  to  bring  about  20  cubic  centi- 
meters of  fuming  nitric  acid  into  a  small  porcelain 
dish,  which  is  covered  with  an  inverted  funnel,  and 
introduce  gradually  3  to  4  grammes  of  the  rubber 


300   INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

in  fine  shreds.  A  violent  evolution  of  gas  takes 
place  and  the  rubber  is  destroyed.  When  decom- 
position is  complete,  the  excess  of  nitric  acid  is  re- 
moved by  evaporation  upon  the  water-bath,  and 
the  residue  is  mixed  with  about  4  grammes  of  a 
mixture  of  3  parts  potassium  nitrate  and  4  parts 
soda,  and  fused  at  a  gentle  heat.  The  residue  is 
taken  up  with  water,  and  after  adding  hydrochloric 
acid,  evaporated  to  dryness,  to  separate  silicic  acid 
and,  in  the  solution  filtered  from  it,  the  sulphuric 
acid  is  determined.  In  the  presence  of  lead  or  bar- 
ium combinations,  sulphate  of  lead  or  of  barium  is 
found  with  the  silicic  acid  and  has  to  be  separated 
from  it. 

Determination  of  antimony.  Put  in  a  porcelain 
crucible  about  1J  grammes  of  the  sample  cut  up  in 
very  small  pieces,  together  with  10  grammes  of  crys- 
talized  calcium  sulphide.  Heat,  at  first  gently,  and 
when  foaming  ceases  more  vigorously,  and  finally 
bring  to  a  gentle  red  heat,  stirring  occasionally  with 
an  iron  wire.  After  cooling  take  up  the  fused  mass 
with  water,  filter  off  separated  coal,  etc.,  filter  and 
super-saturate  the  filtrate  with  hydrochloric  acid, 
whereby  a  mixture  of  antimonious  sulphide  and 
sulphur  is  precipitated.  This  mixture  is  collected 
upon  a  weighed  filter,  dried  at  212°  F.,  weighed, 
and  in  a  portion  taken  from  the  filter  and  weighed? 
the  antimony  is  determined. 

Determination  of  calcium.  Ignite  the  rubber  in  an 
open  porcelain  crucible  until  a  white  ash  remains 
behind.  This  is  lu  ated  with  hydrochloric  acid,  the 


EXAMINATION    OF    RUBBER    ARTICLES.          301 

resulting  fluid  compounded  with  an  abundant  quan- 
tity of  hot  water,  supersaturated  with  ammonia, 
whereby  antimonious  oxide  is  separated,  after  filter- 
ing precipitated  with  oxalic  acid,  and  from  the 
separated  calcium  ^oxalate  the  quantity  of  calcium 
is  determined. 

In  a  sample  of  rubber,  Unger  found  by  this 
method  : 

Sulphur  .  .  .  5.72  per  cent. 
Antimony  .  .  .  6.813  percent. 
Calcium  .  .  .  0.3046  per  cent. 

The  calcium  is  calculated  to  sulphate,  the  anti- 
mony to  pentasulphide,  and  the  remaining  sulphur 
taken  into  account  as  such.  According  to  this  the 
sample  examined  would  contain  : 

]l.:'.o5  per  cent,  pentasulphide  of  antimony  (with  4.542  per  cent,  sulphur). 
1.310  per  cent,  gypsum  (CaSo4.2H20  .  .  (with  0.244  per  cent,  sulphur). 
0.934  per  cent,  sulphur (with  0.934  per  cent,  sulphur). 

86.401  per  cent,  rubber (with  5.720  per  cent,  sulphnr). 

100.00    per  cent. 

It  is  doubtful  whether  in  rubber  vulcanized  at  a 
high  temperature,  crystallized  calcium  sulphate 
with  2  molecules  of  water  is  present,  and  it  would 
be  more  correct  to  take  gypsum  in  an  anhydrous 
state  into  the  calculation. 

From  the  result  of  the  analysis,  Unger  calculates 
that  the  mass  to  be  vulcanized  consisted  of  rubber, 
100  parts,  and  pentasulphide  of  antimony,  15.74, 
or  perhaps  more  correctly,  16  parts,  and  that  the 
pentasulphide  used  had  the  following  composition  : 


302    INDIA  RUBBER,  GUTTA  PERCH A,  BALATA. 

Pentasulphide  of  antimony,  85.50  per  cent.;  gyp- 
sum, 9.63  ;  free  sulphur,  6.87. 

To  ascertain  the  nature  of  other  mineral  filling- 
substances,  a  complete  analysis  of  the  ash  has  to 
be  executed.  With  admixtures  containing  lead  it 
must  be  taken  into  consideration  that  the  sulphur 
is  converted  into  sulphate  of  lead. 

For  the  detection  of  admixtures  of  organic  sub- 
stances, such  as  cork  meal,  etc.,  it  is  advisable  to 
subject  thin  sections  previously  swelled  up  as  much 
as  possible  in  carbon  disulphide  to  a  microscopical 
examination. 

For  the  detection  of  a  content  of  oily  substitutes 
which  are  frequently  mixed  in  larger  quantities  with 
rubber,  Henriques  recommends  to  boil,  from  six  to 
eight  hours,  2  to  5  grammes  of  the  substance,  cut 
up  in  small  cubes,  with  about  ten  times  the  quan- 
tity of  alcoholic  soda  solution  which  contains  6  to 
8  per  cent,  of  sodium  hydroxide.  Only  a  very  small 
quantity  of  rubber  is  dissolved,  but  the  total  quan- 
tity of  the  oily  substances,  together  with  a  portion 
of  the  sulphur,  passes  into  solution,  while  a  part  of 
soda  present  enters  into  an  insoluble  combination 
with  the  sulphur. 


III.  BALATA. 
CHAPTER  XV. 

HISTORY,  OCCURRENCE  AND  USES  OF  BALATA. 

LIKE  gutta  percha,  balata  is  the  inspissated  milky 
juice  of  a  few  plants  of  the  family  Sapotaceae,  which, 
however,  belong  exclusively  to  the  genus  Mimusops. 
It  was  formerly  considered  identical  with  gutta 
percha,  but  it  is  distinguished  from  it  by  suffi- 
ciently characteristic  differences  to  assign  to  it  a 
more  independent  position. 

Balata  became  first  known  about  45  years  ago, 
the  first  account  of  it  being  found  in  an  article 
published  in  1857,  by  Prof.  Bleekrode,  and  in  a 
communication  made,  the  same  year,  by  him  to 
the  Society  of  Arts.  In  these  communications  he 
designated  balata  as  Sumatra  gutta  percha,  and 
concluded  that  it  was  a  product  identical  with  that 
obtained  from  Isonandra  gutta.  In  1860,  the  Colon- 
ial Secretary  of  British  Guiana  forwarded  to  the 
Society  of  Arts  a  few  specimens  of  balata  collected 
by  Van  Hoist  in  Berbice,  which  were  later  on 
turned  over  to  the  Kew  Museum.  The  same  so- 
ciety having  offered  a  prize  for  the  best  substitute 
.for  gutta  percha,  received  in  February,  1864,  other 
samples  of  balata  from  Sir  William  Holmes.  In 
(303) 


304        INDIA    RUBBER,   GUTTA    PERCH A,   BALATA. 

bis  letter  to  the  Secretary  of  the  Society,  Holmes 
states  that  at  the  International  Exposition  of  1862, 
he  had  exhibited  about  |  Ib.  of  balata,  which  later 
011  had  been  handed  over  to  Charles  Hancock,  who 
had  expressed  a  very  favorable  opinion  in  regard  to 
it.  This  sample  was  also  sent  to  the  Kew  Museum, 
and  the  same  institution  received  other  samples  as 
follows:  from  James  Collins,  18G8,  from  British 
Guiana;  from  Governor  Longdon,  1874,  from 
Trinidad,  and  from  Im  Thurm,  1882,  from  Deme- 
rara.  In  1884,  G.  S.  Jenman  forwarded  samples  of 
balata,  as  well  as  balata  milky  juice,  and  of  balata 
prepared  by  precipitation  with  alcohol. 

The  genus  Mhrmsops  is  distributed  over  almost 
the  entire  globe,  but  thus  far  trees  yielding  balata 
are  only  known  to  occur  in  America  :  In  the  Antilles 
and  Bahama  Islands  (West  Indies),  in  Venezuela, 
British,  Dutch  and  French  Guiana,  and  a  portion 
of  Brazil  ;  in  Africa  :  On  the  west  coast  of  the  equa- 
torial region,  Abyssinia,  Angola,  Madagascar  and 
Mauritius;  in  Australia:  In  Queensland  and  New 
Zealand.  Hence  the  home  of  balata  is  in  an  en- 
tirely different  location  from  that  of  gutta  percha. 

Mimusops  Balata  is  the  principal  balata-yielding 
tree.  It  is  indigenous  to  English,  Dutch  and 
French  Guiana,  Surinam,.  Barbadoes  and  the  An- 
tilles, Brazil  (Amazon),  Costa  Rica.  It  is  a  largo 
tree,  with  a  trunk  about  6  feet  in  diameter,  and 
furnishes  a  wood  much  sought  after  as  a  building 
material.  The  Dutch  name  Paardenfleseh  (horse- 
flesh), is  given  on  account  of  the  wood  being  of  the 


HISTORY    OP    BALATA.  305 

color  and  having  the  appearance  of  horse-flesh. 
The  hark  is  thick  and  rough,  and  the  fruit  is  of 
the  size  of  a  coffee  berry,  sweet  like  a  plum,  and 
with  a  hard  white  kernel,  which  yields  an  oil  bitter 
in  taste.  The  leaves  are  glossy,  oval  and  acumin- 
ated. The  milk  is  drunk  by  the  natives,  and  when 
diluted  with  water,  used  as  cow's  milk.  The  trees 
grow  in  groups,  and  in  alluvial  soil. 

Besides  M/ in n tops  Balata,  the  following  varieties 
of  MiiHUMjjM  which  yield  balata  may  be  mentioned  : 
M.  (/lolmMi,  M.  spec-iosa,  M.  Schimperi,  M.  Kiimmel; 
further  Lucumus  varieties:  L.  gigantea,  L.  fissilis,  L. 
litxt'iociirjKi,  L.  laurifolia,  L.  procera,  and  finally  a 
few  varieties  of  Chrysophyllum. 

For  obtaining  the  balata  latex  it  is  not  sufficient 
to  make  simply  incisions  in  the  bark,  as  the  milky 
juice  of  Mimusops  is  so  thick  and  coagulates  so 
rapidly  that  the  incisions  would  soon  be  choked  up. 

In  Venezuela  the  collectors  formerly  sawed  the 
trees  off  near  the  foot,  raised  them  upon  props,  and 
placed  vessels  under  them  for  the  collection  of  the 
juice  which  exuded  from  numerous  incisions  made 
scarcely  a  foot  apart  from  each  other.  By  this  bar- 
barous method  about  7  to  13  Ibs.  of  balata  were  ob- 
tained from  a  tree  of  medium  size.  At  the  present 
time  hand-presses,  by  which  the  bark  is  subjected  to 
strong  pressure,  are  used.  One  press  yields  in  an 
hour  9  to  13  quarts  of  juice  which  is  equal  to  from  4 
to  7  Ibs.  of  dry  balata.  In  Maturin,  a  region  which 
embraces  the  Venezuelan  provinces  of  Cumania, 
Barcelona,  Guiana,  and  Isla  Margarita,  very  large 
20 


306    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

trees  are  found  from  which  by  this  process  several 
hundredweight  of  balata  are  obtained.  Hence  this 
system  of  destruction  is  extraordinarily  lucrative, 
and  is  so  widely  extended  that,  if  continued,  this 
source  will  soon  be  exhausted,  notwithstanding  the 
great  abundance  of  balata  trees  in  Maturin. 

In  Dutch  Guiana,  especially  in  Surinam,  the 
trees  are  tapped.  The  bark,  up  to  a  height  of  20 
feet,  is  provided  with  incisions  which  are  connected 
with  each  other  and  so  arranged  that  the  juice  from 
one  gutter  runs  into  the  other  until  it  reaches  the 
lowest  one,  where  it  is  caught  in  a  calabash,  from 
which  it  is  later  on  poured  into  a  larger  vessel  pro- 
vided'with  a  handle,  which  is  called  "gooba."  In 
this  gooba  the  juice  is  carried  to  the  settlement,  and 
either  sold  as  it  is,  or  poured  into  shallow  wooden 
evaporating  dishes.  As  the  water  evaporates  the 
surface  hardens,  and  skins  about  J  inch  thick  are 
formed,  which  are  removed  and  hung  up  over  lines 
to  drain  and  dry.  This  drying  requires  several 
weeks,  since  every  balata  skin  presents  a  hard  sur- 
face which  retards  evaporation.  A  gallon  of  juice 
yields  4  Ibs.  of  dry  balata.  A  tolerably  skilled 
workman  obtains  *about  4  gallons  of  milk  a  day, 
and  a  very  skilled  one  up  to  10  gallons. 

In  British  Guiana  the  jnethod  of  gathering  balata 
is  more  rational  as  far  as  the  preservation  of  the 
trees  is  concerned.  Several  longitudinal  incisions 
are  made  in  the  trunk  of  the  tree,  and  the  bark 
between  them  is  removed.  The  liber  or  inner 
bark,  however,  is  left  standing,  which  makes  the 


HISTORY    OF    BALATA.  307 

formation  of  new  bark  possible.  The  most  suitable 
method  is  to  remove  and  leave  the  bark  standing 
in  alternate  squares.  The  bark  removed  is  then 
pressed,  ,a  medium-sized  tree  yielding  by  this 
method  about  2  Ibs.  of  balata  ;  but  it  must  be  taken 
into  consideration  that  this  operation  can  be  indefi- 
nitely repeated,  since  every  succeeding  year  the  pieces 
of  bark  previously  left  standing  are  taken.  The 
juice  flows  most  abundantly  during  the  rainy  sea- 
son, and  it  also  coagulates  more  slowly  during  that 
period.  The  milk  which  is  called,  in  British 
Guiana,  "  Purvio,"  is  collected  in  wooden  vessels, 
since  iron  vessels  impart  to  it  a.  blackish  color, 
which  depreciates  the  commercial  value  of  the 
product. 

Crude  balata  is  gray,  brown,  or  white-reddish 
with  darker  spots  and  veins ;  in  appearance  it 
resembles  dry  skins  and  it  feels  soapy  to  the  touch. 
Gray  balata  comes  into  commerce  also  in  blocks 
about  32  inches  long  and  16  inches  wide,  but  red 
balata  only  in  sheets  J  to  f  inch  thick.  The  sheets 
show  the  shape  of  the  vessel  used  for  evaporating 
the  juice.  The  commercial  article  contains,  as  a 
rule,  few  foreign  bodies,  and  little  bark.  Lime  is 
frequently  added,  especially  more  recently  where 
the  natives  adulterate  the  juice  by  an  addition  or 
water,  and  then  add  lime  to  give  the  product  the 
necessary  consistency.  At  an  average  the  quantity 
of  impurities  amounts  to  10  per  cent. 

The  balata  from  Mimuspps  Balata  and  M.  globosa 
are  especially  valued  since,  besides  their  great 


308    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

strength,  they  posses  the  property  of  being  ductile 
only  in  a  very  slight  degree,  which  makes  them 
especially  suitable  for  the  manufacture  of  belts. 
They  bring  as  high  and  even  a  higher  price  than 
gutta  percha. 

In  his  "  Cantor  Lectures  on  Gutta  Percha,"  pre- 
viously referred  to,  Dr.  E.  F.  Obach  gives  valuable 
statistical  data  regarding  the  price  and  export  of 
balata  from  British  and  Dutch  (Juiana.  These 
data  have  been  taken  partly  from  government  re- 
ports on  the  colonies  and  parti)7  from  communica- 
tions of  the  Director  of  the  Colonial  Museum  at 
Haarlem,  as  well  as  from  a  report  of  Mr.  Churchill, 
consul  at  Paramaribo,  to  the  Marquis  of  Salisbury. 

For  the  period  from  .1885  to  1896,  they  are  as 
follows  : 


Export  from 

Export  from 

British  Guiana. 

Dutch  Guiana. 

Year. 

Cwts. 

Value  £. 

Year. 

Cwts.     Value  £ 

1885 

496 

2213 

1886 

606 

2979 

1887 

723 

3498 

1888 

2219 

14069 

1889 

30 

116 

1889 

3245 

15625 

1890 

1502 

7951 

1890-91 

2025 

10078 

1891 

1882 

11950 

1891-92 

1039 

6807 

1892 

2375 

15086 

1892-93 

2120 

11296              1893 

641 

5424 

1893-94 

1832 

8283              1894 

2132 

18047 

1894-95 

1867 

11484              1895 

2(131 

22281 

1895-96 

1424 

8923 

1896 

2480 

21000 

Total. 

17S96 

951  S2 

Total. 

13673 

101865 

HISTORY    OF    BALATA.  309 

The  above  table  shows  that  the  lowest  average 
price  of  a  pound  of  balata  exported  from  British 
Guiana  was  9.13  pence  in  1885,  and  the  highest, 
14.17  pence,  in  1888;  while  the  lowest  average 
price  per  pound  exported  from  Dutch  Guiana  was 
9.0-7  pence  in  1889,  and  the  highest,  18.14  pence 
in  1893  and  1896.  It  must,  however,  be  taken 
into  consideration  that  this  calculation  of  price  is 
based  upon  the  declared  value  in  the  export  har- 
bors. On  the  other  hand  the  selling  price  in  the 
European  markets,  Liverpool,  London,  Marseilh^r 
Rotterdam  and  Hamburg  was  considerably  higher 
and,  in  London,  varied  during  the  last  fifteen  years 
for  balata  in  sheets  and  blocks  1/1  to  2/6  per  pound. 

The  principal  difference  between  gutta  percha 
and  balata  shows  itself  in  the  manner  in  which  the 
two  products  are  influenced  by  the  air.  While 
gutta  percha,  by  the  action  of  air  and  light,  be- 
comes rapidly  resinous,  hard  and  brittle,  not  only 
upon  the  surface,  but  also  in  the  interior,  if  this 
action  continues  for  some  time,  balata,  under  the 
same  conditions,  remains  unaltered  for  a  long  per- 
iod. At  the  ordinary  temperature  it  is  softer  than 
gutta  percha,  and  after  cooling,  does  not  acquire  the 
same  degree  of  solidity.  On  the  whole  it  cools 
slowly,  and  when  mixed  with  gutta  percha,  trans- 
mits this  property  to  the  mixture.  When  heated 
it  diffuses  the  same  odor  as  pure  gutta  percha 
which  has  been  slowly  heated  under  water  and 
then  brought  to  boiling.  Its  specific  gravity  is 
1.05.  It  can  be  cut  like  gutta  percha.  but  is 


310    INDIA  RUBBER,  GUTTA  PERCHA,  BALATA. 

tougher.  It  dissolves  completely  in  turpentine, 
but  especially  so  in  benzene  and  carbon  disulplride 
when  heated.  Like  rubber  and  gutta  percha,  it 
resists  caustic  alkalies  and  acts  in  the  same  manner 
towards  hydrochloric  acid.  By  sulphuric  acid  it  is 
carbonized.  At  the  ordinary  temperature  it  forjns 
a  horn-like  mass,  but  softens  at  120°  F.,  and  in  this 
state  can  be  given  any  desired  form. 

When  the  commercial  article  is  purified  by  wash- 
ing in  boiling  water,  to  which  a  small  quantity  of 
acid  has  been  added,  and  then  in  boiling  alcohol,  a 
mass  is  obtained  which,  when  dissolved  in  carbon 
disulphide,  filtered  and  evaporated,  shows,  according 
to  Sperlich,  the  same  composition  as  gutta  percha 
namely  :  Carbon,  88.5  ;  hydrogen,  11.3  per  cent. 

Crude  balata  is  worked  in  a  manner  similar  to 
gutta  percha,  the  same  apparatus  and  machines 
being  used.  In  most  cases,  however,  the  manipu- 
lation is  much  simpler,  because  balata,  as  a  rule, 
contains  fewer  impurities  than  gutta  percha,  and 
besides  it  is  not  used  for  articles  for  such  delicate 
purposes  as  the  latter.  Frequently  simple  washing 
in  a  hollander  suffices  as  a  preparation  for  further 
working.  Some  varieties  furnish,  when  vigorously 
kneaded,  a  very  homogeneous  material  which,  how- 
ever, retains  too  much  elasticity  and  remains  ad- 
hesive. Purified  balata  is  also  less  pliant  than 
gutta  percha  and.  without  being  mixed  with  the 
latter,  can  only  be  used  for  certain  purposes.  Un- 
mixed it  is  not  suitable  for  covering  wires  for  the 
purpose  of  insulation,  and  even  when  mixed  with 


HISTORY    OF    BALATA.  311 

the  best  quality  of  gutta  percha  it  is  of  less  value  for 
this  purpose  than  pure  gutta  percha  of  even  second 
quality.  On  the  other  hand,  additions  of  balata  to 
gutta  percha,  and  even  to  rubber,  are  very  proper 
to  give  both  of  them  qualities  desired  for  certain 
purposes.  Unmixed  balata  is  used  for  the  prepara- 
tion of  matrices  and  moulds  for  galvanoplastic  pur- 
poses, for  shoe-soles,  sweat-bands  and  particularly 
machine  belts.  For  the  manufacture  of  the  latter  it 
is  especially  suitable  on  account  of  its  great  tough- 
ness ;  but,  like  gutta  percha  belts,  they  must  not  be 
used  in  very  warm  rooms,  as  otherwise  they  become 
sticky.  The  manufacture  of  balata  belts  is  analogous 

FIG.  24. 


\ 


to  that  of  rubber  belts.  The  best  quality  of  strong 
cotton  tissue  is  used  for  the  purpose,  and  is  treated 
with  prepared  mass  in  the  spreading  calender  or 
spreading  machine,  then  folded  together  to  the  re- 
quired thickness,  frequently  provided  with  longitud- 
inal seams,  and  then  pressed  either  in  that  state  or 
after  it  has  received  upon  one  or  both  sides  a  cover- 
ing sheet.  It  is  scarcely  necessary  to  say  that  these 
belts  do  not  require  vulcanizing.  The  ends  of  this 
kind  of  belt  can  be  joined  together  by  a  very  sim- 


312    INDIA  RUBBER,  GUTTA  PERCH  A,  BALATA. 

pie  joint,  which  is  made  as  follows  :  Heat  the  two 
ends  until  they  are  sticky,  then  spread  the  belt  out 
flat,  Fig.  24,  push  the  two  ends  so  far  one  over  the 
other  that  a  cut  made  at  an  angle  of  45°  slopes  both 
ends  suitably  towards  each  other,  bring  the  edges 
|  to  1  inch  over  each  other,  press  with  an  iron, 
replace  the  now  jointed  belt  in  its  original  folds 
and  subject  the  joint  to  pressure.  When  the  joint 
is  cold  the  belt  can  be  placed  in  position  and  runs 
without  pounding  or  knocking,  and  hence  is  especi- 
ally suitable  for  driving  dynamo  machines. 


INDEX. 


ABSOLUTE  alcohol,  preparation 
of,  69,  70 
Accrah,  81,  82 
Acids,  behavior  of  gutta  percha 

towards,  253.  254 
Aco's  process  of  utilizing  waste, 

292,  293 
Africa,  cut! ing  down  rubber  trees 

in,  29 
Africa,  rubber  plants  of,  13 

tapping  rubber  trees  in,  32 
African  rubber,  79-86 
Air,  effect  of,  upon  rubber,  63 
Albane,  properties  of,  250 
Alexandre,  Cabriot   and  Duclos, 
first  patent   for  the  utilization 
of   gutta  percha,  obtained  by, 

226 
Alcohol,  absolute,  preparation  of, 

69,  70 

use  of,  in  coagulation,  52 
Alstonia,  12 
Alum,  coagulation  by,  49,  50 

use  of,  in  coagulation,  53 
Amazon,  Lower,  mode  of  tapping 
rubber  trees  on  the,  30-32 
Upper,  mode  of  tapping  rub- 
ber trees  on  the,  32 
America,  rubber  plants  of,  13 
American    process    of    bleaching 

rubber,  163 
receipt   for   artificial    ivory, 

165,  166 
rubber,  74-79 
Ammonia,  liquid,  addition  of,  to 

the  latex,  36 
Angola,  coagulation  of   the  latex 

in,  42,43 
niggers,  85 

Animal  charcoal,  bleaching  gutta 
percha  with. 2  79- 
281 


Animal  charcoal,  use  of,  for  deo- 
dorizing vulcan- 
ized rubber,  145, 
146 

Antimony,  determination  of,  300 
pentasulphide,  105 

vulcanization  with,  128 
Apocynaceae,  10-12 
Artificial    ivory,     preparation   of, 

159-166 
whalebone,  or  balenite,  137, 

138 

Artocarpus,  10 
Aruwimi,  83 
i  Asbestos,  105 
\  Asclepiadeae,  12 
Asclepias,    rubber    in   the  milky 

juice  of,  7 
1  Asia,  cutting  down   rubber   trees 

in,  29 

tapping  rubber  trees  in,  32,  33 
Asiatic  rubber,  86-88 
'  Assahan,242 
Assam,  coagulation  of  the  latex 

in,  46,  47 
cultivation  of  rubber  plants 

in,  16 

rubber,  86.  87 

Aubert  and  Gerard's  process  for 
making  round  rubber  threads, 
177-179 

Australia,  rubber  plants  of,  13 
tapping  rubber  trees  in,  33 
Australian  rubber,  88 

BACJAN.  237,  238 
Bahia,  76,  77 

coagulation  of  the  la- 
tex in,  46,  47 

Balata  and  gutta  percha,  princi- 
pal difference  between,  309 
belts. manufacture  of,3 1 1 ,312 


(313) 


314 


INDEX. 


Balnta,  crude,  properties  of,  307 

working  of,  310-312 
export  of,  from   British  Gui 

•ana,  308 
Dutch  Guiana, 

308 
history,  occurrence,  and  uses 

of,  303-312 

mode  of  obtaining,  305-307 
price  of,  309 
specific  gravity  of,  309 
statistics  of,  308,  309 
unmixed,  uses  of,  311 
Balenite  or  artificial  whalebone, 

137,  138 
Balloons,  small  toy,  171,  172 

vulcanizing  of,  125 
Balls,  rubber,  169 

small  solid,  171 
Bands,  vulcanizing  of,  125 
Banjer-massin,  238 
Bassia  Parkii,  229 
Baumhauser's     investigation     of 

gutta  percha,  251 
Belts,    balata,    manufacture     of, 

311,  312 
machine,  joining  the  ends  of, 

311,312 

vulcanizing  of,  125 
Benguela  niggers,  85 
Benzene,  solubility  of  rubber  in, 

67 

Berniard,  experiments  of,  3 
Berthollet,  studies  of,  3 
Besson,  efforts  of,  3,  4 
Bicycle  tires,  190-192 
Billiard  tables,  cushions  for,  vul- 
canizing of,  125 
Billiongs,^230 
Bissao  balls,  79 
Bleached  gutta  percha,  Cattell's, 

281,  282 
Bleaching  gutta  percha,  278-282 

rubber,  160-164 

Bleekrode,   Prof.,  account  of  ba- 
lata by,  303 
Bolungan,  240 

Boots  and  shoes,  water  proof  coat- 
ing for,  220 

Borneo  (Ben  Koclen),  88 
dambose,  62 


Borneo  Djambes,  88 
rubber,  88 

mode  of  obtaining,  29 
Bornesite.  62 
Borrache,  74 
Boula-Balam,  243 
Brass  moulds,  126 
Brazil,    coagulation  of  the   latex 

in,  43-46 
preparation  of  rubber  in,  35- 

40 

Bread  fruit,  10 
Breit,  W.,  first  submarine  cable 

laid  by,  227. 
British  Guiana,  export  of  balata 

from,  308 

mode    of   obtaining 
balata  in,  306,307 
Buffers,  vulcanizing  of,  125 
Bumba,  83 

Burghardt's    condensing  appara- 
tus, 212,  213 
Busira,  83 

Buttons,  composition  for,  156 
Butylene,  72 

CABEQA  de  negro,  75 
Cahuchu,  8 

Calcium    chloride,   use  of,  in  co- 
agulation, 52 

determination  of,  300-302 
Calender,  107,  108 
Callotropis  procera,  12 
Cameraria,  11 
Camphor,  133 

Caou-tchene,  composition  of,  72 
Caout-Chou,  2 
Caoutchouc,  1 
mineral,  3 
oil  of,  69 

bodies  present  in,  72 
composition  of,  71 
Caoutchoucine,  69 

composition  of,  71 
Carbon,  decrease  of,  in  rubber,  64 
disulphide  and  alcohol,  solu- 
tion of  rubber  by,  69, 
70 

objection    to,    as    a    sol- 
vent, 6S 
solubility  of  rubber  in, 67 


INDEX. 


315 


Carthagena,  77 
Casamanza  (Boalam),  80 

(Gambia),  80 
Cassava,  9 
Castilloa,  9 

coagulation   of  the  latex  of, 

40,  41,  46,  47 
cultivation  of.  15 
elastica,  best  development  of, 

in  Mexico,  23,  '14 
indigenous  to  Mexico,  22 
seed  of,  24,  25 
Cattell's   bleached  gutta  percha, 

281.  282 
Caucho,  77,  78 
Cayenne,  77 
Ceara,   preparation   of  rubber  in, 

44,  45 
rubber,  properties  of,  45 

solubility  of,  07 
scraps,  9,  75,  76 

coagulation  of  the  latex 
in  the  preparation  of, 
43-46 

Cecropia,   10 
Central   Africa,  rubber  plants  of, 

13 

America,  rubber  plants  of,  13 
coagulation  of  the  latex 

in,  46,  47 
tapping  rubber  trees  in, 

32 
American  rubber,  78,  79 

sheets,  78,  79 
Ceylon,    cultivation     of    Manihot 

in,   18 
of  Para  rubber  tree 

in,  18-20 
rubber,  87 
Chalk,  105 
Champagne's  varnish  for  morocco, 

219,  220 

Champion,  efforts  of,  4 
Charcoal,  animal,  bleaching  gutta 
percha  with,  279- 
281 

use  of,  for  deodor- 
i/ing  vulcanized 
rubbir.  145,  146 

Chattertou's    gutta    purcha  com 
pound,  290 


Chay, 229 

Chemical  and  physical  properties 

of  crude  rubber,  60-73 
Chemical  and  physical  properties 

of  gutta  percha*  246-254 
Chiapas,    rubber   plantations    in, 

28 

Chloride  of  iron,  use  of,  in  coagu- 
lation, 52 
Chlorine,  bleaching  rubber  with, 

161-163 
Chloroform,  bleaching  gutta  per 

cha  with,  278,  279 
solubility  of  rubber  in,  67 
Chonemorphia,  12 
Chromic  acid,  use  of,  in  coagula- 
tion, 52 
Cinnabar.  105 
Clark  and  Miller,  experiments  of, 

upon  gutta  percha,  251,  253 
Clark's  patent  felt,  208,  209 
Cloth  printing  machinfs,  jacket  of 

pressure  rolls  of,  172,  173 
Coagulation  by  alum,  49,  50 

by  artificial    dry  heat  or  fu- 
migation, 35-40 
by    combination    of   natural 
or     artificial     heat     with 
chemical      disintegration, 
56-58 
by    moi^t    artificial   heat  or 

by  boiling,  40,  41 
by  natural  heat,  41,  42 
by  natural  heat;  evaporation 
upon    the    human     body, 
42,43 

by  natural  heat;  evaporation 
upon    other  even  surfaces 
than  the  ground, 43— 46 
by  rest  after  the  addition  of 
four  to  five  times  the  quan- 
tity of  water.  47,  48 
by  skimming  after  the  addi- 
tion of  the  same  quantity 
of  water,  and  a  shorter  or 
longer  rest,  46,  47 
by  soap  water,  50,  51 
by    sulphuric    acid    and    sea 

salt,  50 

experiment  in,  by  Grandjean 
and  Waser,  38,  39 


316 


INDEX. 


Coagulation  of  the  latex,  33-60 
summary  of  experience,  and 

experiments  in,  58—60 
Coal  tar  asphaltum,  138 
Coating  wires  with  gutta  percha, 

269-276 

Cochin   China,  acclimatizing  ex- 
periments in,  22 
Coffigny.   description   of  a   plant 

by,  2  ' 

Coins,  taking  impressions  of,  282 
Cold  vulcanization,  6.  110-114 

bath  for,  111 
Coli,  241 
Collins.  J.,  on  Strauss'  process  of 

coagulation,  49 
Colon  rubber.  78 
Coloring  substances,  129,  130 
Columbia,  cultivation    of  rubber 

plants  in,  22 
Virgen,  77 

Combs,  composition  for,  155 
Commercial  gutta  percha, 235-245 

rubber,  73-91 

Compound  tires,  classes  of,  191 
Compounds  of  gutta  percha,  282- 

286 
of  gutta  percha  and    wood, 

286,  287 
of  rubber   and  gutta  percha, 

282,  283 
Congo,  coagulation  of  the    latex 

on  the,  42,  43,  47,  48 
cultivation  of  rubber  trees  on 

the,  20-22 
Cords,  square,  from  crude  rubber, 

173-176 
from  prepared  rubber, 

176,  177 
Cork  meal,  detection  of  admixture 

of,  302 
Corrosive    sublimate,    use    of,    i» 

coagulation,  52 
Costa  Rica,  cultivation  of  rubber 

plants  in,  22 
Cotonan,  241 
Cousin,  preparation  of  rubber  by, 

55 

Cowrie  copal,  133 
Cross,  Robert,  journeys  of,  15 
Crude  balata,  properties  of,  307 


Crude  balata,  working  of,  310-312 

gutta  percha,  manner  of  ob 

tain  ing,  230-235 

treatment  of,  255- 

262 

rubber,  admixtures  of,  92 
characteristic  peculiari- 
ties of,  109 
chemical    and    physical 

properties  of,  60-73 
composition  of,  61,  62 
cutting  up,  93-f>:> 
drying,  98,  99 
manner    of     obtaining, 

29-33 
mechanical       treatment 

of,  92-108 
operation    of   purifying, 

93 
preparation     of      mixed 

mass  from,  104,  105 
removal    of     impurities 

from,  92,  93 
rolling  or  washing,  95- 

98 
softening   or   superficial 

washing  of,  93 
specific  gravity  of,  61 
square  cords  from,  173- 

176 
washed,  further  working 

of,   99-108 
Cuidad-Bolivar,  il 
Cultivation  of  rubber  plants,  14-29 
Cushions  for  billiard  tables,  vul- 
canizing of,  125 
Cutting  machines,  93-95 

square  cords   from   prepared 

rubber,  176,  177 
up  crude  rubber,  93-95 
Cynanchum,  1  2 

D 'ALMEIDA,  Dr.  Jose,  225,  226 
Dambonite,  62 
Dambose,  62 

Day,  Augustine  G.,  improved 
method  of  vulcanizing 
patented  by,  6 

Decolorizing  rubber,  160-164 
Deodorizing    vulcanized    rubber. 
144-146 


INDEX. 


317 


Deodorizing  water-proof  tissues, 

204-206 
Desulphurized  vulcanized  rubber, 

146,  147 

Deville,  Dr..  observations  by,  39 
Dichloride  of  sulphur,  preparation 

of,  112,  113 
properties  of,  113, 

114 

Dichopsis  calophylla,  229 
gutta,  228 
Krantziana,  229 
oblongifolium,  228 
pustulatum,  229 
Door  knobs,  composition  for,  156 

mats,  vulcanizing  of,  125 
Double    texture   water-proof   tis-  ; 

sues,  192 

Drum  slicing  machine,  256 
Drying  crude  rubber,  98,  99 

loss  in.  99 
Dumas's  process  of  preparing  very  j 

thin  sheets,  193 
Dunlap  tire,  191 
Dusting  hard  rubber,  152,  153 
Dutch   Guiana,  export   of  balata 

from,  308 

mode  of  obtaining  ba- 
lata in,  306 

Dye  works,  printing  rolls  for  use 
in,  172 

EAS.T  Africa,  coagulation  of  the 
latex  in,  41,  42,  43 
rubber  plants  of,  13 
Ebermayer,    hard    rubber    combs 

examined  by,  155 
Ebonite,  65 

moulds,  126 
Ecuador  scraps,  79 
Elastic  gum  wine,  2 

webbings,      fabrication      of, 

209-212 

Electric  wire  and  cables,  machine 
for  insulating,  manufactured  by 
John  Royle  &  Sons,  273-276 
Emery,    conversion    of,  into    fine 

powder,  141,  142 
Enamel,  rubber,  142-144 
Enameling  hard  rubber,  153 
Enamels,  rubber,  colored,  143,  144 


England,  re-export  of  gutta  percha 

from,  244,  245 
Entrefina  Para,  74.  75 
Equator,  83 
Esquebo,  77 

Ether,  solubility  of  rubber  in,  67 
Euphorbia,  9 
Euphorbiacea?,  8.  9 
Eupione,  72 
Examination    of   rubber   article*, 

295-302 

FAUJAS  de  St.  Fond,    investi- 
gations of,  3 
Felt  paper,  208,  209 
Ferric  oxide,  105 
Ficus,  9,  10 

coagulation  of   the    latex  of. 

46,  47 

cultivation  of,  14 
elastica,  2,  10 
Filling  substances,  determination 

of  the  total  quantity  of,  297 
Fine   cut   sheet,   adulteration   of. 

104 
invention    of.   103, 

104 
sheets,  101 

commercial     thick- 
nesses of,  103 
Para  rubber,  74 
Filtering  gutta  percha    solution, 

279-281 
Flint,     conversion    of,    into    fine 

powder,  141,  142 
Fluavile,  composition  of,  250,  251 
Foucroy,  studies  of,  3 
Fresneau,  researches  of,  2 
Fry,   C.,  patented   method  of,  for 
dissolving    rubber    and    gutta 
percha,  70 
Fumeiro.  the,  36 
Fumigation,  coagulation  by,  35- 

40 
Fusel-Aublet,  work  of,  2 

GABOON  balls,  82 
tongues,  82 
Gambia  balls,  80 

coagulation  of   the  latex   in. 
55-58 


318 


INDEX. 


Gerard's  process  of  vulcanization, 

115-117 

Gerner's  preparation  of  hard  rub- 
ber, 133,  134 
Getah  muntali,  235 
Gilder's  varnish  for,  219 
Giobert,  studies  of,  3 
Glass,    conversion    of,    into    line 

powder,  141-144 
Goodyear,  Cha?.,  discovery  of  vul 

canizing  by,  5 
hard  rubber  invented  by,  6 
vulcanizing  process  invented 

by,  117,  118 
Grand  Bassarn,  8 1 
Grandjean  and  Waser.  experiment 

of,  38,  39 
Graphite,  141 

Grinding  and  polishing  composi- 
tions, 139-142 
and  polishing    compositions, 

form  of,  142 
compositions,  preparation  of, 

141 

Grossa,  74,  75 
Grossart,  invention  of,  3 
Guatemala,    coagulation    of    the 

latex  in,  55,  56 
rubber,  79 
Guayaquil,  78 
Guiana,  preparation  of  rubber  in, 

35-40 

Gum  wine,  elastic,  2 
Gutta,  composition  of,  250 
percha,  224-290 

and      balata,     principal 

difference  between, 209 

and  rubber  compound  for 

machine  belts, 

283-285 

waste,  and  its  util- 
ization.291-294 
and  wood,  compound  of, 

286,  287 

appearance      of     best 
known      varieties    of, 
236,  243 
best  known   varieties  of, 

237-243 

bleached,  Cattell's,  281, 
282 


Gutta  percha,  bleaching  of,  278- 

282 

chemical  and  physical 
properties  ot,  246- 
254 

indifference  of,  253 
coating  wires  with,  259- 

276 
commercial,  235-245 

names  of,  236-243 
composition  of,  249 
compound,  Chatterton's, 

290 

compounds,  282-286 
crude,  manner  of  obtain- 
ing, 230-235 
treatment  of,    255- 

262 

c  utting  up,  256 
disguising    the  odor  of, 

286 

export    of,    from    Singa- 
pore, 243,  244 
extraction  of,  234,  235 
forms      of,     in       which 
brought      into     com- 
merce,  236-243 
Fry's    patented    method 

for  dissolving,  70 
hard,  compounds,    285, 

286 
historical      review      of, 

224-227 
hose,  264-267 

machine  for,264, 265 
industrial  application  of, 

263-277 
kneading    machine    for, 

258, 259 
loss  of,  by  washing  and 

kneading.  262 
moulil  ing  articles  of,  264 
occurrence  of,  227-230 
plants,  geographical  dis- 
tribution   of,  230 
plants,  most  impor- 
tant. 228-229 
preparation   of.  2.'>1.  2.'!2 
of,  for  storage,  260, 

261 
press  or  strainer  for,  260 


INDEX. 


319 


Gutta  Percha,  principal  markets 

of,  245 
properties  of  best  known 

varieties  of,  23G-243 
quantities  of,  brought  to 

Singapore,   243 
solution,      filtering     of, 

279-281 
solutions,  R  o  s  s  e  a  u's, 

289,  290 

statistics  of,  243-245 
structure  of,  248 
threads,  267-269 
unmixed. scarcity  of,  232 
uses  of,  263-264 
vulcanization     of.    276, 

277 
washing    machine     for, 

257,  258 
yield  of,  233 
vierge,  242 

HANCOCK,     Thos.,    investiga- 
tions of,  4 

Hancock,  Thos.,   process  of  vul- 
canization, invented  by,  6 
warm  vulcanization  invented 

by,  114 
Hancornia,  11 

coagulation  of  the  latex  of, 

46,  47 

Ilanausek,  T.  F.,  experiments  of, 

on  the  solubility  of  rubber,  67 

Hard    gutta    percha    compounds, 

285,  286 

rubber,  65,  148-166 
coloring,  152 
compositions  for,  155 
dusting  of,  152,  153 
enameling,  153 
Gerner's  preparation  of, 

133,  134 
invention  of,  6 
lacquer,  222,  223 
moulding      articles     of. 

140,  150 
moulds,  120 

physical    and    chemical 
properties  of,  158,  159 
plating,  153 
uses  of,  149 


Hard    rubber,   vulcanizing,    150- 
152 

waste,  utilization  of,  154 
Hay  ward,  uses  of  flowers  of  sul- 
phur by,  5 

Heat,  artificial  dry  or  fumigation, 
coagulation  by,  35-40 
behaviour  of  rubber  in,  71—73 
Heater,  vulcanizing,  121-123 
Heavy  spar,  105 
Hemp,  ground,  105 

seed,  133 

Henriques'  method  of  detecting 
oily  substitutes, 
302 

of  determining  sul- 
phur, 299,  300 

Herissant,  investigations  of,  2,  3 
Hevea,  8 

brasiliensis,  8 

chemical  composition  of 

the  latex  of,  61 
cultivation  of,  15,  16 

of,  in  Ceylon,  18-20 
properties    of  the    fresh 

latex  of,  60,  61 
composition    of     the    milky 

juice  of,  37 
guyanensis,  2,  8 
latex  of,  experiments  in  treat- 
ing the,  51-54 
Heveene,  composition  of,  72 
Historical  review  of  rubber,  1-6 
Hoehnel,  Dr.  F.  von,  and  Collins 
Jones,  various  methods  of  coag- 
ulation described  by,  34 
Hollow  articles,  169,  170 
Hose-forging  machines,  266,  267 
gutta  percha,  264,  267 
rubber,  179,  180 
small,    manufacture   of,  182, 

183 

vulcanizing  of,  125 
with  layers  of  wire.  182 
Howison,  James,  2 

INDIA,    cultivation    of    rubber 
plants  in,  14,  15 
India  rubber,  1-223 

occurrence  of,  7-14 
plants  of,  13 


320 


INDEX. 


Indian  Archipelago, cutting  down 
rubber  trees  in.  2!» 

Industrial    application     of   gutta 
percha,  263-277 

Insulating  electric  wire    and  ca- 
bles, machine  for.  21'.', -27<> 

Iodine,  tincture  of.  use  of,  in   co- 
agulation. 53 

Ipomoea  bona  nox,  56 

Iron,  chloride,  use  of.  in  coagula- 
tion, 52 

Isonandra  gutta,  22S 

Isoprene,  composition  of,  72 

Isthmus  of  Tehuantepec,  Castil- 
loa  elastica  indigenous  to,  22 

Ivorv,    artificial,    paeparation  of. 

159-166 
black     10f, 

JATROPA  elastica,  8 
Java  rubber,  87,  88 
Jebe,  74 

Jeffery's  marine  glue,  222 
Johnson's  hard   rubber  mixture, 

157 

method  of  preparing  water- 
proof tissues.  196 
Jungfleisch.  E.,  experiments  of,  in 
extracting  gutta    percha,   234, 
235 

KAMPTULICON.       preparation 
of,  133-136 
Kassa'i.  noir,  82 

in  balls,  H3 
rouge,  82 
strips,  83 
Kelatin,   241,  242 
Kew  Botanical    Garden,   cultiva- 
tion of  rubber  plants  in  the, 
15 
Museum,  specimens  of  batata 

received  by,  303.  304 
Kneading  machines,  258,  25!) 
Knife  handles. composition  for,  156 
Knives,  sharpening  and  polishing 

compositions  for.  1  to 
Kotaringin,  238 

LA  COXDAMINK.  researches  of, 
1.2 


Lacquers   and    varnishes,    rubber, 

214-223 
Lacquer,  hard  rubber,  222,  223 

leather,  2 is 
La  Grenee,  introduction  of  gutta 

percha  by. 2 2 6 
Lamp  black.  1  05 
Landolphia,  1 1 

coagulation  of    the    latex   of. 

47,  4H 
Latex,  addition  of  liquid  ammonia 

to.  :-',<) 

chemical    disintegration    of. 
by    mineral    reagents, 
48-54 
by  addition  of  vegetable 

agents.  55,  5«; 
coagulation  of  the,  33-HO 
of,  by  alum.  49.  5<t 
of,    by    combination     of 
natural     or     artificial 
heat     with     chemical 
disintegration,    56-58 
of,    by    moist    artificial 
heat    or    by    boiling. 
40,  41 

of,  by  natural  heat,41,  42 
of.  by  natural  heat;  evap- 
oration upon   the  hu- 
man body,  42,  43 
of,  by  natural  heat;  evap- 
oration     upon     other 
even  surfaces  than  the 
ground,  43-46 
of,  by  skimming  after  the 
addition  of    the   same 
quantity  of  water,  and 
a    shorter    or    longer 
rest,  46,  47 

of,  by  soap  water,  50,  51 
of.  by  sulphuric  acid  and 

sea  salt.  50 
fresh,  composition  of,  37 

of      Hevea     brasiliensis, 

properties  of,  60,  61 
modes  in  which  the  coagula- 
tion   of    the.     is    effected, 
:I4,  35 
of  rubber   plants,    properties 

of.  7 
Para,  composition  of.  8 


INDEX. 


321 


Leather  lacquer,  218 

Leuconotis,  11 

Liberia  rubber,  81 

Libreville,  botanical  garden  at,  20 

Light,    change    produced    by,    in 

rubber,  62 
Linseed  oil,  boiled,  206,  207 

solution  of  rubber  in,  69 
Litharge,  105 
Liver   of    sulphur,     solution    of, 

115, 116 
Liverpool,  crude  rubber  imported 

at,  89 
Loando  niggers,  84,  85 

thimbles,  84 

Lock  plates,  composition  for,  156 
London,    importations   of   rubber 

at,  90 
Lopari,  83 

Lower  Congo  (thimbles),  84 
Loyalty  Islands,   coagulation  in, 

38,  39 

Luedersdorf,  observation  of,  5 
Luvituku,  84 

MACHADO,  30 
Machine  belts,  balata,  man- 
ufacture of,  311,  312 
Machine  belts,  gutta  percha  and 
rubber  compound  for, 

283-285 
joining  the  ends  of, 

311,  312 

Mackintosh,   Chas.,    creation     of 
the    industry    of 
water- proof   gar- 
ments by,  4 
first  use  by,  of  rub- 
ber in  the  manu- 
facture of  water- 
proof tissues,  192 
invention  of  fine  cut 

sheet  by, 103 

Macquer,  investigations  of,  2 
Madagascar,     coagulation  of  the 

latex  in,  55,  56 
rubber,  86 
Manguba,  11 

Manihot,     acclimatizing    experi- 
ments with,  16-18 
glazowii,  9 

21 


Manihot  Hipii,  9 
utilissima,  9 
Manioc  or  manihot,  9 
Manisoba,  9 
Maranham,    76 

coagulation  of  the  latex  in,  50 
Marine  glue,  220,  221 

for  damp   walls,  221, 

222 

Jeffery's,222 
Maragula,  237 
Massai  niggers,  81 
Masticating  machine,  100,  101 
Matezite,  62 

dambose,  62 

Matrices,  mixture  for,  283 
Matto  Grosso,  coagulation  of  the 

latex  in,  50 
Para,  75 

Maturin,  mode  of  obtaining  ba- 
lata in,  305,  306 
Mayang  Baton,  229 
Mazer  wood,  224 
Mechanical    treatment   of    crude 

rubber,  92-108 

Medals,  taking  impressions  of,282 
Merlon,  R.  V.,  process  of  coagula- 

described  by,  43,  47,  48 
Mexican  scraps,  79 

sheets,  78,  79 

Mexico,    coagulation  of  latex  in- 
'    40,  41 
cost  of  establishing  a  rubber 

plantation  in,  29 
cultivation  of  rubber  plants 

in,  22-29 
starting  a  regular  plantation 

of  rubber  trees  in,  25-28 
Micrauda,  8 

composition    of     the    milky 

juice  of,  37 

Milk  bottles,  fittings  for,  167 
Milkweed,    rubber  in    the    milky 

juice  of,  7 
Milky  juice,  methods  of  obtaining 

the,  29 
of  Hevea  and  Micranda, 

composition  of,  37 
of  rubber  plants,  pro- 
perties of,  7 
quantity  of,  12 


322 


INDEX. 


Mimusops,   229 

balata,  304,  305 
geographical  distribution  of, 

304 
varieties  of,  yielding  balata, 

305 
Mineral  caoutchouc,  3 

reagent?,    chemical    disinte- 
gration by,  48—54 
Mixing  machine,  106 
Mongabeira,  76 
Mongala,  83 

Montgomery,  Dr.  Wm.,  investiga- 
tion of  gutta  percha  by,  225 
Morellet,    Dr.,     examination      of 
Madagascar  rubber  by,  55 
on  Strauss'  process  of  coagu- 
lation, 49 

Morgan  and  Wright  tire,  192 
Morisse,   Dr.,  experiments    of,   in 
treating    the    latex   of    Hevea, 
51-54 

Morocco,  varnish  for,  219,  220 
Moss  rubber,  188,  189 
Moulding    apparatus    for    round 

threads,  177.  178 
articles  of  gutta  percha.  264 
Moulds,  125,  126,  170 
Moulds,  metals  for,  125.  126 

mixture  for,  283 
Mozambique  balls,  85,  86 
marbles,  85 
spindles,  86 
Mustard  seed,  133 

NADIER,  invention  of,  4 
New  Caledonia,  coagulation 

in,  38,  39 

New  Caledonia  rubber,  88 
Newton's    method    of      utilizing 

waste,  293,  294 
mixture  for  hard  rubber,  157 
Nicaragua,    coagulation    of    the 

latex  in,  46,  47,  55,  56 
scraps,  79 
Niger  niggers,  82 
Nigger    head,  preparation    of,  3, 
40 

solubility  of,  67 
heads,  75,  85 
Nipples,  167 


OAXACA,  Castilloa  elastica  in- 
digenous to,  22 
Occurrence  of  gutta  percha.  227- 

230 

Ochre,  105 

Oil.  effect  of  upon  rubber,  63 
of  caoutchouc,  69 

bodies  present  in,  72 
composition  of,  71 
of  turpentine, removing  water 

from,  68 
solubility  of  rubber  in. 

67 

Oily  substitutes,  detection  of.  302 
Oxidation  of  rubber,  63 

PADONG,  87,  88 
Page,  Prof.,  on  the  structure 

of  gutta  percha,  248 
Pahang,  236,  237 

white.  242 

Palaquium  gutta,  228 
Palm  nuts,  use  of,  in  fumigating 

36 

Panama  rubber,  78 
Para  blanc,  75 

entrefina,  preparation  of.  :-!!». 

40 

latex,  composition  of,  8 
Grossa,  preparation  of,  3!*.  -in 
rubber,  fine,  74 

preparation  of,  35-40 
tree,    cultivation    of,    in 

Ceylon,  18-20 
Sernamby,  75 
Parameria,  1 1 
Parangs,  230 

Parkes,    cold    vulcanization    in- 
vented by,  110 
cold  vulcanization    patented 

by,  6 
Payen,   Anselrne,  examination  of 

gutta  percha  by,  250 
experiments  of,  109,  llo 
Payena  Lerii,  229 
Pedang,  239 
Pekang,  238 
Penang,  87 

Pentasulphide  of  antimony,  vul- 
canization with,  128 
of  potassium,  115 


INDEX. 


323 


Periploca  Graeca.  12 
Pernambuco,  76 

coagulation  of  the  latex   in, 

49,  50 

Peru,  coagulation  of  the  latex  in, 

50,  51,  55,  56 
cultivation  of  rubber  plants 

in,  22 
in  slabs,  77,  78 

Peruvian  balls,  78 

Petroleum,    anhydrous,    prepara- 
tion of,  114 

Phenolsulphonic  acid,  use  of,  in 
coagulation,  52 

Pierre,  R.,  acclimatization  of  rub- 
ber plants  by,  20,  21 

Pitch,  addition  of,  to  rubber,  131, 
132 

Plastite,  138,  139 

Plating  hard  rubber,  153 

Pneumatic   tires,  classes  of,  190, 
191 

Polishing  and  grinding  composi- 
tions, 139-142 

Pontianak,  239 

Potassium  pentasulphide,  115 

Press  or  strainer  for  gutta-percha. 
260 

Priestley,    application    of  rubber 
recommended  by,  3 

Printing    rolls    for    use    in     dye 
works,  172 

Propagation  of  Hevea,  19 

Pump  valves,  vulcanizing  of,  125 

RANGOON,  87 
Raw  material,  rubber,  1-91 
Recovery  of  solvents,  212,  213 
Resin,  cheap  rubber  masses  with 

an  addition  of,  132 
Reunion,    acclimatizing     experi- 
ments in,  22 

Rings,  thick,  vulcanizing  of,  125 
Rollers,  composition  for,  156 
Rolling  crude  rubber,  95-98 
Rolls  for  cutting  thread,  175 
Round  rubber  threads,  177-179  • 
Rousseau's  conclusions  regarding 

coagulation,  54 
solutions  of  gutta-percha  and 
their  use,  289,  290 


Roxburgh,  discoveries  of,  2 
Royle,  John,  &  Sons,  machine  for 
insulatingelec- 
tric  wires  and 
cables,  manu- 
factured by, 
273-276 

tubing    machines 
manufactu  red 
by,  183-188 
Rubber,  absorption  of  water  by, 

64 

addition  of  pitch  to,  131,  132 
American,  74-79 
and  gutta-percha  compounds, 

282,  283 
and  gutta-percha  waste  and 

its  utilization,  291-294 
and  sulphur,  chemical  com- 
bination between,  118,  1.10 
appearance    of    best    known 

varieties  of,  74-88 
articles,  best  known  in  gen- 
eral use,  167 
examination  of,  295-302 
vulcanized  with    penta- 
sulphide of  antimony, 
examination  of,  298 
bags,  1 
balls,  169 

behavior  of,  in  heat,  71-73 
of,  towards  solvents,  65- 

71 
of,  towards  sulphur,  64, 

65 
blocks  of,  102 

cutting      up      of,      into 

sheets,  102,  103 
bottles,  1 
change  produced  in,  by  light, 

62 
cheap,  with    an    addition   of 

resin,  132 
coloring,  129.  130 

of,  by   chemical    combi- 
nations, 130,  131 
commercial,  73-91 

names  of,  74-8S 
composition  of,  72 
compounds,  129-147 
black,  130 


324 


INDEX. 


Rubber  compounds,  blue,  129 
green,  130 

manufacture    of   water- 
proof fabrics  by  means 

of.  206-208 
red,  129 
rough, 131 
violet,  130 
white,  129 
yellow,  129f  130 
content  of  water  in,  63 
crude,  admixtures  of,  92 

characteristic  peculiari 

ties  of,  109 
chemical    and    physical 

properties  of,  60-73 
composition  of,  61,  62 
cutting  up,  93-95 
drying,  98,  99 
importations  of,  at  Liv- 
erpool, 89 
of,  at  London,  90 
of,     by     the     principal 

European       countries 

and        the          United 

States,  90 
kneading    and    mixing, 

105,  106 
manner    of      obtaining, 

29-33 
mechanical  treatment  of, 

92-108 
operation    of  purifying, 

93 
preparation     of     mixed 

mass  from,  104,  105 
principal  classes  of,  73 
removal  of  impurities 

from,  92,  93 
softening  or    superficial 

washing  of,  93 
specific  gravity  of,  61 
square  cords  from,  173- 

176 
decolorizing  and   bleaching, 

160-164 

decrease  of  carbon  in,  64 
effect  of  air  upon,  63 
of  oil  upon,  63 
of  water  upon,  64 
enamel,  142-144 


Rubber  felt,  208,  209 

forms  of,  in    which    brought 

into  commerce,  74-88 
Fry's  patented    method     for 

dissolving,  70 
hard,  65,  148-166 
coloring,  152 
composition  for,  155 
dusting  of,  152,  153 
enameling,  153 
Gerner's  preparation  of, 

133,  134 
invention  of,  6 
lacquer,  222,  223 
moulding      articles     of, 

149, 150 

physical    and    chemical 
properties  of,  158,  159 
plating,  153 
uses  of,  149 
vulcanizing,  150-152 
historical  review  of,  1-6 
hose,  179,  180 

ordinary      manufacture 

of,  180-182 

with  intermediate  layers 
or  stiffeners,  182,  183 
India,  1-223 

occurrence  of,  7-14 
industry,  actual  date  of  com- 
mencement of,  4 
leather,  136,  137 
loss  in,  by  washir.g  and  dry- 
ing, 99 
mechanical   combination   of, 

with  sulphur,  117,  118 
method  of  effecting  a  com- 
plete solution  of,  67,  68 
most  suitable  solvents  for,  69 
oxidation  of,  63 
pervious  to  perspiration,  133 
places  of  origin  of,  74-88 
plantation,  cost  of  establish- 
lishing  a,  in  Mexico, 29 
starting    a,   in    Mexico, 

25-28 

plants,  age  of,  at  which  they 

can  be  tapped,  12,  13 

arrangement  of,  in  four 

families,  8 
cultivation  of,  14-29 


INDEX. 


325 


Rubber  plants,  cultivation  of,  on 

the  Congo,  20-22 
geographical  groups  of, 

13 

nursery  for  raising,  27 
properties  of  the  milky 

juice  or  latex  of,  7 
soil  required  by,  13.  14 
prepared,      cutting      square 

cords  from,  176,  177 
prices  of,  91 

principal  markets  of,  89 
properties  of  best  known  va- 
rieties of,  74-88 
raw  material,  1-91 
rolling  or  washing,  95-98 
sheets,   thick,   prevention    of 

warping  of,  126 
shoes,  189,  190 

solution    for    repairing, 

220 

vulcanized,  6 
•    soft,  manufacture  of  articles 

from,  167-213 

solubility  of  different  varie- 
ties of,  66 

solution  of,  in  linseed  oil,  69 

solutions,  efforts  to    prepare 

water-proof  garments 

by  means  of,  4 

kneading   of,    apparatus 

for,  216,  217 
importance  of,  65 
preparation  of,  214-218 
sponges,  188,  189 
statistics  of,  88-91 
substances    capable    of    dis 

solving,  65,  66 
threads,  invention  of  cutting, 

4 

preparation  of,  173 
round,  177-179 
weaving  of,  210-212 
toys,  168,  169 

trees,    obtaining    the    milky 
juice  by  cutting  down 
the,  29,  30 
tapping  of,  30-33 
tubes,  preparation  of,  3 
varnishes  and  lacquers,  214- 
223 


Rubber  vulcanized,  65 

and     cloth,    fabrics 

of,  195 

deodorizing,  144—146 
desulphurized,       146, 

147 

discovery  of,  5 
which    does    not    swell 
up  in  contact  with 
fat,  133 

washed  crude,  further  work- 
ing of,  99-108 
white  masses  of,  132 
world's  production  and  con- 

sumpt'on  of,  89 
yielding  plants,  habitat  of,  7 

OACHACAMUTE,  56 

^         Saigon,  garden  at,  22 

Sandakan,  237 

Sarapong,  239,  240 

Sarawak,  238,  239 

Schwanitz's    vulcanized    rubber, 

133 

Sea  salt  and  sulphuric  acid,  co- 
agulation by,  50 
Senegal  balls,  79 
Seringa,  8 

fina,  74 

Sernamby  de  Borracha,  75 
de  Caucho,  78 
de  Jebe,  75 
de  Perou,  78 
preparation  of,  39,  40 
Shellac,  addition  of,  to  hard  rub- 
ber, 156,  157 
Shoes     and     boots,      waterproof 

coating  for,  220 
Siak,  240 

Siemens,  W.,  first  construction  of 
telegraph  lines  insulated  with 
gutta  percha  by,  227 
Sierra  Leone  niggers,  81 

rubber,  solubility  of,  67 
twist,  81 
Singapore,  export  of  gutta  percha 

from,  243,  244 
handling  of  gutta  percha  in, 

235,  236 

quantity     of     crude     gutta 
percha  brought  to,  243 


326 


INDEX. 


Single  texture  waterproof  tissues 

192 

tube  tires,  191 
Siphonia  Brasiliensis,  8 

elastica,  8 

Soap  water,  coagulation  by,  50,  51 
Soft      rubber,    manufacture      of 

articles  from,  167-213 
Softening  of  crude  rubber,  93 
Solutions,  rubber,  preparation  of, 

214-218 

Solvents,  behavior  of  gutta  percha 
towards,  248,  249 
of  rubber  towards, 

65-71 

recovery  of,  212,  213 
Sorel's    gutta   percha  compound, 

288,  289 
Souni,  239,  240 
South  America,  rubber  plants  of, 

13 
tapping  rubber  trees  in, 

32 

American  rubber,  74-78 
Specific  gravity,  mode  of  deter- 
mining, 29V 
of  crude  rubber,  61 
utility  of,  in  examining 
rubber    articles,    295, 
296 

Spreading  machine,  198,  199 
Square  cords  from  crude  rubber, 

173-176 
from    prepared    rubber, 

176,  177 

threads,  cutting  of,  104 
Statistics  of  balata,  308,  309 
of  gutta  percha.  243-245 
of  rubber,  88-91 
Stones,  removal    of,   from    gutta 

percha,  255,  256 
Strainer  or  press  for  gutta  percha, 

260 

Strauss,    Heinrich   A.,  process  of 

coagulation  invented  by,  49,  50 

Sulphur    and    rubber,    chemical 

combination  between,  118, 

119 

behavior  of  rubber  towards. 

64,  65 
determination  of,  298-300 


Sulphur  dichloride,    preparation 

of,  112,  113 
properties  of,  113,  114 
Sulphur,  liver  of,  solution  of,  115, 

116 
mechanir-al    combination    of 

rubber  with,  117,  118 
Sulphuric  acid  and  phenolsul- 
phonic  acid, 
mixture  of,  for 
c  oagu  1  ation, 
53,  54 

and  sea  salt,  co- 
agulation by, 
50 

use  of,  in  coagu- 
lation. 52 

Surinam,-    mode      of      obtaining 
balata  in,  306 

TABASCO,    rubber    plantations 
in,  28 

Table  of  export  of  balata  from 
British  and 
Dutch  Guiana, 
308 

of  gutta  percha. 
244 
of  importations  of  rubber  at 

Liverpool,  89 
of rubber  at  London, 

90 

of  rubber  by  the 
principal  Euro- 
pean countries 
and  the  United 
States,  90 

of    world's    production    and 
consumption  of  rubber,  89 
Talc,  141 

powder,  dusting  with,  126 
Tapioca,  9 

Tapping,  quantity  of  sap  obtained 
from  each, of  150  trees,  31, 

32 

rubber  trees,  30-33 
Tehuantepec,  Isthmus  of,  Castil- 

loa  elastica,  indigenous  to,  22 
Telegraph    cable,   protection    of, 

272, 273 
cables,  manufacture  of,  270 


INDEX. 


327 


Telegraph    wires,    insulation    of, 

270 

Thior,  229 

Thread-cutting  machine,  175,  176 
Threads,   apparatus  for  pressing, 

268 

for  elastic  webbing,  210 
gutta  percha,  267-269 
manufacture    of,  by    rolling, 

269 

preparation  of,  173 
square,  cutting  of,  104 
stretching  of,  179 
weaving  of,  210-212 
Tin,  moulds  of,  125,  126 
Tires,  bicycle,  190-192 
Tissues  with  an  intermediate  layer 

of  rubber,  203,  204 
Tobacco  pouches,  167 
Toluene,  use  of,  for  extracting 

gutta  percha,  234,  235 
Tool  handles,  composition  for,  156 
Toy  balloons,  small.   171,  172 
Toys,  rubber,  168,  169 
Tradescant,   John,  gutta   percha 

first  introduced  by,  224 
Tringanon,  242,  243 
Tubes  for  laboratories,  167 

rubber,  preparation  of,  3 
Tubing    machines    manufactured 
by  John  Royle  and  Sons, 
Paterson,  N.  J.,  183-188 
short,  manufacture  of,  181 
Turner's  process  of  vulcanization, 
128 

UELLE,  83,  84 
Ulmacea?,  9,  10 

Unger's  directions  for  examining 
rubber  articles  vulcanized  with 
penta-sulphide  of  antimony, 298 
United  States,  importation  of  rub- 
ber by  the,  90 
Upper  Congo  rubber,  83 
Urceola,  11 

elastica,  cultivation  of,  15 
esculenta,  cultivation  of,  15 

VAHEA,  10,  11 
Varnish,  flexible,  220 
Varnish  for  gilders,  219 


Varnish  for  morocco,  219,  220 

slow  drying,  219 
Varnishes    and   lacquers,  rubber, 

214-223 
Vegetable  agents,  disintegration 

by  the  addition  of,  55,  56 
Velours,  169 
Velvet  balls,  169 
Venezuela,  mode  of  obtaining  ba- 

lata  in,  305,  306 
preparation  of  rubber  in,  35- 

40 

Vera  Cruz,  Castilloa  elastica  in- 
digenous to,  22 
Virgin  sheets,  75 
I  Vulcanite,  65 
I  Vulcanization,  109-128 
cold,  6,  110-114 

bath  for,  111 

condition  on  which  the  tem- 
perature for,  depends,  120 
discovery  of,  5 
Gerard's  process  of,  115-117 
Goodyear's  process,  117,  118 
limit  of  temperature  for,  120 
mode  of  effecting,  109 
modified,  127 
of  gutta  percha,  276,  277 
Turner's  process  of,  128 
warm,  114, 115 
with    pentasulphide  of  anti- 
mony, 128 
Vulcanized  rubber,  65 

and   cloth,   fabrics. 

of,  195 
deodorizing,    144- 

146 
desulphurized,  146, 

147 

discovery  of,  5 
which      does      not 
swell  up  in  con- 
tact    with     fat, 
133 

Vulcanizing  apparatus,  121-125 
articles  requiring  only  light 

treatment,  127,  128 
brick  chambers  for,  121 
hard  rubber,  150-152 
heater,  121-123 
improved  method  of,  6 


328 


INDEX. 


Vulcanizing    in    two    operations, 

126,  127 

operation,  118-120,   125-128 
process,  distinctive    features 
of,  110 

WALLS,    damp,    marine    glue 
for,  221-222 

Warm  vulcanization,  114,  115 
Washed    crude    rubber,    further 

working  of,  99-108 
Washing  crude  rubber,  95-98 
loss  in,  99 

machine,  95-97,  257,  258 
superficial,  of   crude  rubber, 

93 
Waste,  rubber  and  gutta  percha, 

and  its  utilization,  291-294 
Water,  absorption    of,  by  rubber, 

64 

content  of,  in  rubber,  63 
effect  of,  upon  rubber,  64 
proof  fabrics,  manufacture  of, 
by  means  of  rub- 
ber    compounds, 
206-208 

tissues  employed  in 
manufacture     of, 
194,  195 
garments,  creation  of  the 

industry  of,  4 
efforts    to   prepare, 
by  means  of  rub- 
ber solutions,  4 


Water  proof  tissues,  deodorizing, 

204-206 
tissues,  manufacture 

of,  192-208 
spreading    machine 

for,  198,  199 
Webbings,  elastic,  fabrication  of 

209-212 

Welwitsch,  Dr.,  process  of  coagu- 
lation, described  by,  43 
West  Africa,  rubber  plants  of,  13 
Indian  scraps,  79 
sheets,  78,  79 
Whalebone,  artificial,  or  balanite, 

137,  138 

Wheatstone's  idea  of  a  telegraph 
line  between  England  and  the 
Continent,  227 

Wheel-cutting  machine,  256,  257 
White  rubber  masses,  132 
Willis,  J.  C.,  circular  of,  18 
Wire,  apparatus  for  coating  with 

gutta  percha,  270-272 
Wires,  coating  of,  with  gutta  per- 
cha, 269-276 

Wood  and  gutta  percha,  com- 
pounds of,  286.  287 


'VINC,  coating  moulds  with,  125 
*J         white,  105 


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